JP2759007B2 - Vehicle position correction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle position correcting method, and more particularly to a vehicle position correcting method for correcting vehicle position information detected by dead reckoning on a road by map matching processing by a projection method.

[0002]

2. Description of the Related Art There is an on-vehicle navigator that provides guidance for driving a vehicle so that a driver can easily reach a desired destination. In this in-vehicle navigator, the position of a vehicle is detected, map data around the vehicle position is read from a CD-ROM, a map image is drawn on a V-RAM, and a vehicle position mark is overlaid on the map image. -Output the image from the RAM to a CRT display while converting it into a video signal, and display it 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 understood at a glance.

The map stored in the CD-ROM is divided into regions of appropriate longitude and latitude widths according to the scale level, and roads are represented by vertices (nodes) represented by longitude and latitude coordinates. ). A portion connecting two nodes is called a link, and a road (road link) is formed by connecting one or more links.

In a dead reckoning navigator, for example, a vehicle position is detected by integration based on outputs of a distance sensor and a relative direction sensor. FIG. 6 is an explanatory diagram showing a vehicle position detection method by dead reckoning navigation. The distance sensor outputs a pulse every time the vehicle travels a certain unit distance L ₀ , and when the reference direction (θ = 0) is the positive direction of the X axis and the counterclockwise direction from the reference direction is the + direction, When the last determined vehicle position is the point P ₀ (X ₀ , Y ₀ ) and the vehicle direction (absolute direction in the vehicle traveling direction) at the point P ₀ is θ ₀ , the relative position at the time of traveling the unit distance L ₀ The direction sensor output is Δθ ₁
When there were at, heading theta ₁ at L ₀ point P ₁ which proceeds from P _{0 is, θ 1 = θ 0 + Δθ} 1 ·· (1) , and the change in the vehicle position, ΔX = L ₀ · cos θ ₁ ΔY = L ₀ · sin θ ₁ , and the position coordinates (X ₁ , Y ₁ ) at the current point P ₁ are: X ₁ = X ₀ + ΔX = X ₀ + L ₀ · cos θ ₁ ··· (2) Y ₁ = Y ₀ + ΔY = Y ₀ + L ₀ · sin θ ₁ ··· (3) Therefore, if the vehicle azimuth and position coordinates at the start point are given, thereafter, every time the vehicle travels the unit distance L ₀ ,
By repeating the calculations (1) to (3), the vehicle position can be detected in real time.

However, since the distance sensor and the relative azimuth sensor have errors, the vehicle position detected by dead reckoning accumulates errors as the vehicle travels and deviates from the road. For this reason, the vehicle-mounted navigator corrects the vehicle position detected by dead reckoning on the road by comparing it with the road data in the map data (map matching processing). 7 to 9 are explanatory diagrams of map matching by the projection method. The vehicle position determined last time is the point P _i-1 (X
_i-1, located in the Y _i-1), vehicle direction is assumed to be a θ _i-1 (in Fig. 7 point P _i-1 shows the case does not match the road RD _a). If the relative orientation [Delta] [theta] _i of when the pulse from the distance sensor to a predetermined distance L ₀ traveling from the point P _i-1 is output, a point P _i of the estimated vehicle position dead reckoning '
The vehicle orientation θ _i at (X _i ′, Y _i ′) and P _i ′ is
From equations (1) to (3), θ _i = θ _i−1 + Δθ _i X _i ′ = X _i−1 + L ₀ .cos θ _i Y _i ′ = Y _i−1 + L ₀ .sin θ _i .

At this time, (a) Point P_i'Which can drop a vertical line from
So point P_i′ The vehicle direction θ_iAnd the angle formed by the link
Is within a certain value and the point P_i′ To the link
Search for a vertical line whose length is within a certain distance. This
Here is Road RD_aUpper direction θ_a1Link LK_a1(node
N_a0And N_a1And a road RD_bUpper direction θ_b1of
Link LK_b1(Node N_b0And N_b1). (B) Point P_i'From link LK_a1, LK_b1Hanging down
Line RL_ia, RL_ibLength, and the shorter one has the highest priority.
The first candidate for high map matching, the longer one is priority 2
The second highest map matching candidate is set. here
Is link LK_a1Is the first candidate, link LK_b1Is the second candidate
Become. (B ') You are perpendicular RL_iaAnd RL_ibWhen the lengths are the same
Is the link LK_a1, LK _b1Of which, the vehicle direction θ_iAngle with
The smaller one is the first candidate, and the larger one is the second candidate. (C) And the link LK of the first candidate_a1To the projection target
And point P_i-1And point P_i′ Running trajectory SH_iTo the perpendicular R
L_iaPoint P in the direction of_i-1Is link LK_a1Above (or link
LK_a1To the point P_i-1
And P_i'Movement point PT_i-1And PT_i(D) Finally, the point PT_i-1PT around_i'Is the link L
K_a1Up (or link LK_a1On the extension of
Roll and move to obtain the moving point and determine the vehicle position P_i(X _i, Y
_i).

Here, the determined vehicle position P_iThe absolute direction at
θ_iWill be left as is. Also, the link corresponding to (a)
If not found, estimated vehicle position P_i′ As it is
Vehicle position P_i(X_i, Y_i). Further, as shown in FIG.
Point P, which is the last determined vehicle position_i-1Is road RD_aTo
When there is a moving point PT_i-1Is the point P_i-1Matches. Ma
Also, as shown in FIG._i-1Turn around the intersection at
Vehicle measurement position P_i'Is the road RD in map matching_bInteract with
Road RD to insert_aProjected vehicle position P projected above _i(X
_i, Y_i).

In the step (b) described above, the priority order is determined by the length of the perpendicular line dropped from the estimated vehicle position P _i ′ to the link. However, the link is formed by the vehicle direction θ _{i at the} point P _i ′. The order of priority may be determined by the size of the angle. Specifically, a smaller angle between θ _i and the link is defined as a first candidate, and a larger angle is defined as a second candidate.

As described above, by detecting a vehicle position by combining dead reckoning and map matching, an accurate vehicle position can be obtained while correcting errors of the distance sensor and the relative direction sensor.

[0010]

SUMMARY OF THE INVENTION
In map matching by such a projection method, the pattern
Unlike matching, L₀Vehicle position for every minute distance
Therefore, as shown in FIG._dNo
Nk LK_d1Vehicles that have traveled at a relatively small angle
After passing the branching junction (intersection) CT, the road RD_d
Link LK_d2, Road RD_eLink LK_e2, Road RD
_fLink LK_f2When entering any one of the
The way of traveling, errors of distance sensor, relative direction sensor, etc.
Thus, for example, the determined vehicle position immediately before the branch point CT is P
_j-1The vehicle is on the road RD_dLink LK
_d2Despite entering,_j-1Next inferred vehicle position
Is P _j'Like the road RD_eLink LK_e2Get closer to
Sometimes, P_j′ Is a matching candidate link
LK_d2, LK_e2, LK_f2The link LK _e2
Is closest, so map matching by projection method is performed.
And the vehicle position is wrong and the road RD_eLink LK_e2upper
P_jWill be corrected. And then the vehicle
RD_dAlong the right direction in Fig. 10
Guessed vehicle position P detected by dead reckoning navigation_{j + 1}', P
_{j + 2}', ... are all road RD_eLink LK_e2To
Closed, so fixed by map matching
Vehicle position P_{j + 1}, P_{j + 2}... are all wrong paths
Road RD_eCome on and have regular road RD_dUp
There was a problem that it became impossible to return.

In a map issued by the Geospatial Information Authority of Japan which is referred to when creating road data, for example, a road which runs three-dimensionally at the same place, such as the upper Tokyo Metropolitan Expressway and the lower general road, is a fixed distance in a plane. Since the rule is that they are separated only by a distance, the representation by road data near the junction of the Tokyo Metropolitan Expressway and the general road that run in three dimensions is similar to that in FIG. Therefore, since there is an error in the road data itself, there is a problem that the above-described matching error occurs even if there is no error in the distance sensor or the relative azimuth sensor.

Accordingly, an object of the present invention is to provide a vehicle position correcting method capable of avoiding a map matching error when traveling on a road that branches at a relatively small angle.

[0013]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for calculating a position change of a vehicle each time the vehicle travels a predetermined distance, and estimating the position change by adding the position change to a previously determined vehicle position. Means for obtaining a vehicle position; means for searching for candidate links for matching by projection with reference to the road data in the descending order of priority with respect to the obtained estimated vehicle position; Means for projecting the estimated vehicle position to the current determined vehicle position, and when there are a plurality of candidate links found, at least the candidate link having the highest priority and the candidate link having the second highest priority are located on the vehicle rear side. In this case, when the vehicle branches off from the same node at a predetermined small angle or less, the estimated vehicle position is used as the current determined vehicle position, otherwise, the estimated vehicle position is estimated to be the candidate link with the highest priority. It is achieved by means of a current determined vehicle position by projecting the vehicle position.

[0014]

According to the present invention, every time the vehicle travels a fixed distance, the position change of the vehicle is calculated, and the position change is added to the previously determined vehicle position to obtain the estimated vehicle position. On the other hand, by referring to road data, candidate links for matching by the projection method are searched in descending order of priority, and when there is one candidate link found, the estimated vehicle position is projected on the candidate link to determine the current determined vehicle position. When there are a plurality of candidate links found, at least when the candidate link with the highest priority and the candidate link with the second highest priority branch off from the same node at a predetermined small angle or less on the rear side of the vehicle. The vehicle position is set as the current determined vehicle position as it is, and in other cases, the estimated vehicle position is projected on the candidate link having the highest priority and is set as the current determined vehicle position.
Thus, when the vehicle travels on a road that branches at a relatively small angle, the map matching is temporarily stopped, the vehicle position is detected only by dead reckoning navigation, and after passing through the branching point, the map by the projection method is used. Since the matching is restarted, it is possible to avoid the occurrence of a matching error that is likely to occur at a branch point due to the way of traveling of the vehicle, a sensor error, a road data error, and the like. Correct vehicle position correction on the road can be resumed.

[0015]

FIG. 1 is a block diagram of a main part of an on-vehicle navigator embodying a vehicle position correcting method according to the present invention.

In FIG. 1, reference numeral 1 denotes a CD-ROM serving as map data storage means, and reference numeral 2 denotes an operation panel. Left, right, up, and down scroll keys for scrolling a map with respect to a vehicle position mark, map search, Various keys for enlargement / reduction are provided. 3 relative direction sensor for outputting a relative direction signal by detecting the relative azimuth, 4 is a distance sensor for outputting a pulse indicating that the predetermined distance travel for each traveling predetermined distance L _0.

Reference numeral 5 denotes a microcomputer-configured system controller which displays a map around the vehicle position on a display device described later together with a vehicle position mark. 5a is a map data buffer memory for temporarily storing map data,
b inputs departure point data or fixed vehicle position data from a vehicle position / vehicle direction calculation unit or a vehicle position correction unit, which will be described later, and stores map data around the departure point or vehicle position from the CD-ROM 1 into the map data buffer memory 5a. map read control unit for reading, 5c is the vehicle position and vehicle direction calculation section, relative direction sensor 3, a distance using the respective signals input from the sensor 4 every time the vehicle is a predetermined distance L ₀ traveling, vehicle direction θ And the position change (ΔX, ΔY), and further calculates the current position (absolute longitude, absolute latitude) of the vehicle by dead reckoning by vector-synthesizing the position change with the previous determined vehicle position, And the vehicle direction data.

Reference numeral 5d denotes a vehicle which corrects the vehicle position by map matching based on the projection method and refers to road data in the map data read out to the map data buffer memory 5a based on the estimated vehicle position data, and determines the determined vehicle position as the determined vehicle position. This is a position correction unit. When the predetermined condition is satisfied, the vehicle position correction unit 5d temporarily stops the map matching and sets the estimated vehicle position as the determined vehicle position. In particular,
With respect to the estimated vehicle position, the candidate data for the matching by the projection method is searched in the descending order of priority by referring to the road data, and when there is one candidate link found, the estimated vehicle position is projected on the candidate link and this time determined. When a plurality of candidate links are found as a vehicle position, at least the candidate link having the highest priority and the candidate link having the second highest priority are branched from the same node at the vehicle rear side at a predetermined small angle or less. At this time, the estimated vehicle position is used as it is as the current confirmed vehicle position, otherwise, the estimated vehicle position is projected onto the candidate link having the highest priority and used as the current confirmed vehicle position.

For example, as shown in FIG.
Is assumed to be traveling to the right, and a certain estimated vehicle position P
_j′ Is θ_jWhen θ_jCorner with
When the difference is within a certain value, point P_jLength of vertical line dropped from ′
Links within a certain distance are LK_g1Only one of
If so, the link LK_g1Map matching by projection
The vehicle position is corrected by performing_j
And In contrast, as shown in FIGS. 2 (2) to (4), P
_j'Is a perpendicular RL_gjGyoyo
First candidate link LK_g1(Node N_g0And node N_g1
And the perpendicular RL_hjIs the longer second candidate link L
K_h1(Node N_h0And node N_h1Two straight lines connecting
The point P_j′ Away from the vehicle by the unit length
Point PK _j', First find the link LK_g1
For the point P_j′, Starting point PK _j'To the end point
Tor and Node N_g0Origin, node N_g1To the end point
Kutor (conversely node N_g1Origin, node N_g0The end point
The sign of the inner product of
Node N_g0(Node N_g1), If negative, the end point
Code N_g1(N_g0) Is defined as the node behind the vehicle.

Similarly, for the link LK _h1 , a vector starting at the point P _j ′ and ending at the point PK _j ′ and a vector starting at the node N _h0 and ending at the node N _h1 (inversely, at the node N The sign of the inner product of _h1 may be set as the starting point and the node N _h0 may be set as the ending point. If the sign is positive, the starting node N _h0 (node N _h1 ); if negative, the ending node N _h1.
(Node N _h0 ) is defined as a node behind the vehicle. FIG.
In (2), the nodes N _g0 and N _h0 are specified as nodes behind the vehicle.

Then, each link LK_g1, LK_h1After the vehicle
Node N_g0And N_h0If the coordinates of
One branch node (Fig. 2 (2), (3)) and coordinates
Are non-identical nodes if they are not identical (FIG. 2
(4)). In the case of the same node, the link LK_g1,
LK_h1Angle θ_LIs calculated and given a small angle (eg
For example, when the angle is within 15 °), map matching by the projection method
Estimated vehicle position P without performing _j′
Fixed vehicle position P_j(FIG. 2 (2)). Node N_g0And N
_h0Are not the same (Fig. 2 (4)), or
Even link LK_g1, LK_h1Angle θ_LIs 15 °
Is larger (FIG. 2 (3)), the first candidate link LK_g1To
Map matching by the projection method
Make corrections and confirm vehicle position P_jAnd

5e reads out 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 calculates the fixed vehicle position data and vehicle position / vehicle direction inputted from the vehicle position correction unit 5d. The map drawing control unit outputs the vehicle direction data input from the unit 5c to the display device as vehicle position mark data to display the vehicle position mark.

Reference numeral 6 denotes a display device, which has a CRT controller 7, a video RAM (V-RAM) 8, a read control unit 9, a CRT 10, and the like, and displays a desired map and marks on a CRT screen. .

FIG. 3 is a first flowchart showing the operation of the system controller 5, FIG. 4 is a second flowchart showing the operation of the system controller 5, and FIG. 5 is an explanatory diagram of a vehicle position correcting method by the system controller 5. Hereinafter, description will be made with reference to these figures.

In accordance with the map selection operation by the driver, the map readout control section 5b transfers map data of a predetermined scale including the departure place from the CD-ROM 1 to the map data buffer memory 5a in advance. The unit 5e reads the map data from the map data buffer memory 5a, outputs the map data to the display device 6, and displays the desired map on the CRT 1
It is assumed that the image is drawn on the screen 0.

As shown in FIG. 5, the driver uses the operation panel 2 to set (X ₀ , Y ₀ ) as the position coordinates of the departure place and θ as the vehicle direction.
When configured operation _0, as determined vehicle position P ₀ of the departure point (X _0, Y _0), also, theta as vehicle direction at P _{0 0}
Are initially set in the vehicle position / vehicle direction calculation unit 5c and the like (steps 101 to 104 in FIG. 3). Further, the map drawing control unit 5e outputs the determined vehicle position data (P ₀ ) and the vehicle azimuth data (θ ₀ ) of the departure place to the display device 6 as vehicle position mark data, and outputs the vehicle position mark at a predetermined position on the map screen. Is displayed (step 105).

[0027] When the vehicle starts traveling, for each of predetermined distance L ₀ traveling distance sensor 4 outputs a pulse. When the first pulse is inputted from the distance sensor 4, the vehicle position / vehicle azimuth calculating unit 5 c outputs the relative azimuth signal Δ from the relative azimuth sensor 3.
Enter the theta ₁ (step 106 to 108), setting unit distance L _0, determine the vehicle position coordinates of the departure point _{P 0 (X 0, Y 0} )
And the vehicle direction θ ₀ , and dead reckoning, θ ₁ = θ ₀ + Δθ ₁ ΔX ₁ = L ₀ · cos θ ₁ ΔY ₁ = L ₀ · sin θ ₁ X ₁ ′ = X ₀ + ΔX Y ₁ ′ = Y ₀ + ΔY is calculated to obtain position change amounts ΔX ₁ and ΔY ₁ , and P ₀
Estimated vehicle position P ₁ ′ advanced by L ₀ from
The coordinates of (X ₁ ′, Y ₁ ′) and the vehicle direction θ ₁ are obtained (steps 109 and 110). The data of the estimated vehicle position P ₁ ′ and the vehicle direction θ ₁ are output to the vehicle position correction unit 5d,
The data of the vehicle direction θ ₁ is output to the map drawing control unit 5e.

Subsequently, the vehicle position correcting section 5d searches for the candidate link of the map matching by the projection method in order of priority with reference to the road data stored in the map data buffer memory 5a for the estimated vehicle position P ₁ '(FIG. 4 step 201). That is, a link that can descend a vertical line within a certain length from P ₁ ′ and has an angle formed with the vehicle azimuth θ ₁ within a certain value is given priority as a candidate in the order of the shortest vertical line. And When there is a link having the same perpendicular length, a link with a smaller angle with the vehicle direction is set as a priority candidate. Here, the link LK _k1 on the road RD _k
It is assumed that only (a straight line connecting the nodes N _k0 and N _k1 ) has become a candidate link for matching.

Next, since candidate links have been found (YES in step 202), it is determined whether the number is one (step 203).
d obtains a vehicle position obtained by correcting the estimated vehicle position P ₁ ′ on the link LK _k1 by the projection method, and sets it as a confirmed vehicle position P ₁ (step 204). Then, the map read control unit 5b the determined vehicle position P _1, the vehicle position and vehicle direction calculation section 5
c, Output to the map drawing control unit 5e.

The map reading control unit 5b, based on the current determined vehicle position data input from the vehicle position correction unit 5d,
It is determined whether the map is out of the range of the map previously read out to the map data buffer memory 5a. If the map data is out of the range, the map data newly including the vehicle position is read out from the CD-ROM 1 to the map data buffer memory 5a. The map drawing controller 5e outputs the current determined vehicle position data (P ₁ ) and the vehicle direction data (θ ₁ ) previously input from the vehicle position / vehicle direction calculator 5c to the display device 6 as vehicle position mark data. Then, the vehicle position mark on the map screen is moved and the direction is changed. When the vehicle position deviates from the screen, the map drawing control unit 5e executes the map data buffer memory 5a before moving the vehicle position mark.
The map data for one screen in which the vehicle position is newly entered is read out from the display device 6 and output to the display device 6 to change the display map (the above, the navigation processing, step 11 in FIG. 3).
1).

The vehicle position and vehicle direction calculation unit 5c, when the distance sensor 4 and inputs the second pulse, in the same manner as described above, the relative direction sensor 3 type the relative direction signal [Delta] [theta] _2, L ₀ and the previous Using the vehicle direction θ ₁ , θ ₂ = θ ₁ + Δθ ₂ ΔX ₂ = L ₀ · cos θ ₂ ΔY ₂ = L ₀ · sin θ ₂ is calculated, and the vehicle direction θ ₂ and the position in the X and Y directions are calculated. The amount of change is obtained, and furthermore, X ₂ ′ = X ₁ + ΔX ₂ Y ₂ ′ = Y ₁ + ΔY ₂ is calculated by using the last determined vehicle position P _1, and the estimated vehicle of this time advanced L ₀ from P ₁ The coordinates of the position P ₂ ′ (X ₂ ′, Y ₂ ′) are obtained, the estimated vehicle position data and the vehicle azimuth data are output to the vehicle position correction unit 5d, and the vehicle azimuth data is output to the map drawing control unit 5e (FIG. 3 steps 112, 107-110). And
The vehicle position correction unit 5d stores the map data buffer memory 5a for the current estimated vehicle position P ₂ ′ in the same manner as described above.
The candidate data for the map matching by the projection method are searched in the order of priority with reference to the road data stored in (step 201 in FIG. 4). That is, within a certain distance range from P ₂ ′,
And angle between the vehicle direction theta ₂ looks for a link within a certain value in order of preference. Again, map matching candidates are
It is assumed that only the link LK _k1 on the road RD _k has been reached.

Next, since there is only one matching candidate (YES in steps 202 and 203), the vehicle position correcting section 5d calculates the estimated vehicle position P ₂ ′ on the road RD by the projection method.
calculated vehicle position linked modified on LK _k1 of _k, and determined vehicle position P ₂ (step 204). Then outputs the determined vehicle position P ₂ map read control unit 5b, the vehicle position and vehicle direction calculation section 5c, the map drawing control unit 5e.

The map reading control unit 5b and the map drawing control unit 5e perform predetermined navigation processing based on the current determined vehicle position data and vehicle direction data in the same manner as described above (111 in FIG. 3).

The third pulse is output from the distance sensor 4.
The vehicle position / vehicle direction calculation unit 5c
And the relative azimuth signal Δθ_ThreeEnter the previous vehicle direction θ_Two
To the current vehicle orientation θ_Three, And L₀And θ_Three
Using the current position change ΔX _Three, ΔY_ThreeCalculate and before
Times vehicle position P_TwoTo L₀Predicted vehicle position advanced this time
Place P_Three′ (X_Three', Y_Three') (See FIG. 3).
Steps 112, 107-110). Guess vehicle position P_Three′
And vehicle direction θ_ThreeIs output to the vehicle position correcting unit 5d, and the vehicle
Bearing θ_ThreeIs output to the map drawing control unit 5e.

Subsequently, the vehicle position correcting section 5d outputs the estimated vehicle
Position P_Three'In the map data buffer memory 5a.
Map map by projection method with reference to stored road data
Search for candidate links for switching in priority order (step in FIG. 4)
201). Here, the vehicle is on road RD_kFrom junction (intersection
Point) Three branch roads RD while turning slightly at CT
_k, RD_m, RD_nOne of the RD_mDrive in the direction of
Candidate link is road RD _mLink LK above_m2(Node N_m1
And N_m2And a road RD_kLink LK above
_k2(Node N_k1And N_k2And a road RD_nupper
Link LK_n2(Node N_n1And N_n2Three lines)
But the bending condition at the junction CT and the relative azimuth sensor
3, estimated vehicle position due to errors in distance sensor 4, etc.
P_Three'Is a little road RD_kGet closer, map matching
The first candidate with the highest priority is link LK _k2And two
The second candidate with the second highest priority is the link LK_m2And three
The third candidate with the highest priority is link LK_n2Also became
(See FIG. 5).

At this time, since there are a plurality of matching candidates (YES in step 202, 20)
3) Then, for the first candidate link LK _k2 and the second candidate link LK _m2 , the coordinates of the point PK ₃ ′, which is a unit distance away from the point P ₃ ′ in the vehicle azimuth θ ₃ direction as described above, are obtained. After that, first, for the link LK _k1 , a point P ₃ ′ is started,
A vector ending at the point PK ₃ ′ and a vector ending at the node N _k1 and ending at the node N _k2 ( _inversely ,
The sign of the inner product of _k2 may be the starting point and the node _Nk1 may be the ending point. If the sign is positive, the starting node _Nk1 ( _Nk2 ),
If it is negative, the node N _k2 (N _k1 ) on the end point side is determined as a node behind the vehicle. Here, the node N _k1 on the starting point side is a node behind the vehicle.

Similarly, for the link LK _m2 , a vector starting from the point P ₃ ′ and ending at the point PK ₃ ′, and a vector starting from the node N _m1 and ending at the node N _m2 (inversely, the node N starting from _m2, also may) determine the sign of the inner product of the node N _m1 as an end point, if it is positive, the node N _m1 (N _{m @ 2} of the origin side), if it is negative, the end point node N
_m2 ( _Nm1 ) is determined as the node behind the vehicle (step 20).
5). Here, the node _Nm1 on the starting side is a node behind the vehicle.

If the coordinates of the nodes N _k1 and N _m1 behind the vehicle of the links LK _k2 and LK _m2 are the same, they are determined to be the same branching node. If the coordinates are not the same, the non-identical nodes are determined. (Step 206). Here, the nodes N _k1 and N _m1 have the same coordinates. At this time, the vehicle position correction unit 5d further calculates an angle θ _L formed by the links LK _k1 and LK _m1 (step 207). If the angle θ _L is within a predetermined small angle (here, 15 °), the map by the projection method is used. The estimated vehicle position P ₃ ′ is used as the current determined vehicle position P ₃ without performing matching (Y in step 208).
ES, 209. (See FIG. 5). Then, it outputs the determined vehicle position data P ₃ (= P ₃ ′) to the map read control unit 5b, the vehicle position / vehicle direction calculation unit 5c, and the map drawing control unit 5e. If the links LK _k2 , LK
When the angle formed by the _m2 is determined to be greater than 15 °, compared first candidate link LK _k2 performs map matching by projection modify the vehicle position, the vehicle position after the correction as determined vehicle position P ₃ (Step 210).

The map reading control unit 5b and the map drawing control unit 5e perform predetermined navigation processing based on the current determined vehicle position data P ₃ and vehicle azimuth data θ ₃ input from the vehicle position correction unit 5d (step in FIG. 3). 111). Therefore, immediately after the vehicle has passed the road that branches off at a relatively small angle, the vehicle position mark is not corrected on any road.

The fourth pulse is output from the distance sensor 4.
The vehicle position / vehicle direction calculation unit 5c
And the relative azimuth signal Δθ_FourEnter the previous vehicle direction θ_Three
To the current vehicle orientation θ_Four, And L₀And θ_Four
Using the current position change ΔX _Four, ΔY_FourAnd calculate
These position changes ΔX_Four, ΔY_FourUsing X_Four'= X_Three'+ ΔX_Four Y_Four'= Y_Three'+ ΔY_Four And calculate P_ThreeTo L₀Estimated vehicle position advanced this time
P_Four′ (X_Four', Y_Four') (See FIG. 3).
112, 107-110). Guess vehicle position P _Four'When
Vehicle direction θ_FourIs output to the vehicle position correction unit 5d,
Position θ_FourIs output to the map drawing control unit 5e.

Next, the vehicle position correcting section 5d outputs the estimated vehicle
Position P_Four'In the map data buffer memory 5a.
Map map by projection method with reference to stored road data
Search for candidate links for switching in priority order (step in FIG. 4)
201). This time, the vehicle is Road RD_mRunning on
Therefore, the estimated vehicle position P_Four'Is the link LK_m2Close to
The first candidate is link LK_m2, The second candidate is link L
K_k2, The third candidate is link LK_n2It is assumed that Next
The vehicle position correcting unit 5d determines that there are a plurality of matching candidates.
Therefore (YES in step 202, NO in 203)
Similarly to the first candidate link LK_m2And the second candidate link LK
_k2, A node behind the vehicle is specified (step 2
05), again, node N as before_m1And nodes_k1To
Become. Then, two nodes N_m1, N_k1Compare the coordinates of
(Step 206). The result is the same
Then, link LK_m2And LK_k2Angle
The degree is calculated (step 207), and it is determined whether it is within 15 °.
(Step 208). Since YES, the vehicle position correction unit 5
d is the estimated vehicle position P without matching by the projection method.
_Four'As it is, the determined vehicle position P_Four(Step 20
9), the determined vehicle position data is read by the map reading control unit 5
b, vehicle position / vehicle direction calculation unit 5c, map drawing control unit 5
Output to e.

The map reading control unit 5b and a map drawing control unit 5e performs predetermined navigation processing on the basis of this determined vehicle position data P ₄ and the vehicle bearing data theta ₄ input from the vehicle position correcting unit 5d (step of FIG. 3 111). Therefore, the vehicle position mark is not yet corrected on any road. Thus, the link LK immediately after the turning point of the vehicle
_{During the} passage of _m2 , matching is temporarily stopped and the vehicle position is detected only by dead reckoning navigation.Therefore, depending on how the vehicle travels, sensor errors, road data errors, etc. The position will not be corrected and it will not be impossible to return to the correct road.

The fifth pulse is output from the distance sensor 4.
The vehicle position / vehicle direction calculation unit 5c
And the relative azimuth signal Δθ_FiveEnter the previous vehicle direction θ_Four
To the current vehicle orientation θ_Five, And L₀And θ_Five
Using the current position change ΔX _Five, ΔY_FiveAnd calculate
And the position change ΔX_Five, ΔY_FiveUsing P_FourTo L₀
Estimated vehicle position P advanced this time_Five′ (X_Five', Y_Five')of
Find coordinates (steps 112, 107 to 11 in FIG. 3)
0). Guess vehicle position P_Five′ And vehicle direction θ_FiveIs vehicle position repair
Output to the main part 5d,_FiveIs the map drawing controller 5
e.

Next, the vehicle position correction unit 5d searches for the map matching candidate link by the projection method in the priority order with reference to the road data stored in the map data buffer memory 5a for the estimated vehicle position P ₅ ′ (FIG. 4). Step 2
01). This time, the vehicle by which the vehicle has traveled a certain extent along the road RD _m, first candidate link LK _m3, the second candidate link LK _k2, it is assumed that the third candidate is a link LK _n3. Next, since there are a plurality of matching candidates (YES in step 202 and NO in 203), the vehicle position correcting unit 5d determines whether the first candidate link LK _m3 and the second candidate link LK _k2 are located behind the vehicle in the same manner as described above. Is specified (step 205). At this time, the node behind the vehicle regarding the link LK _m3 is N _m2 , and the node behind the vehicle regarding the link LK _k2 is N _k1 . Therefore, the next step 2
In the comparison of the coordinates of the two nodes N _m2 and N _k1 at 06,
Non-identical. At this time, the vehicle position correcting unit 5d restarts the matching by the projection method and sets the estimated vehicle position P ₅ ′ to the first position.
Performs correction of the vehicle position by projecting the candidate link LK _m3, determined vehicle position P ₅ and then (step 210), the determined vehicle position data map read control unit 5b, the vehicle position and vehicle direction calculation section 5c, map drawing control Output to the unit 5e.

[0045] Therefore, when a predetermined navigation processing on the basis of the map read control unit 5b and a map drawing control unit 5e is currently input from the vehicle position correcting unit 5d determined vehicle position data P ₅ and the vehicle bearing data theta ₅ (FIG. Step 1 of 3
11), the vehicle position mark is moved on the road RD _m traveling. In this way, the vehicle passes the branch point CT on the road RD.
The upper _m to some extent running, if placed past the link LK _{m @ 2} immediately after the branch to the next link LK _m3, and the link LK _m3, link LK _k2 of other roads, between the link LK _n3, distance Therefore, even if the map matching by the projection method is restarted, no matching error occurs anymore, and the vehicle position can be correctly corrected on the traveling road.

The sixth pulse is output from the distance sensor 4.
The vehicle position / vehicle direction calculation unit 5c
And the relative azimuth signal Δθ₆Enter the previous vehicle direction θ_Five
To the current vehicle orientation θ_Five, And L₀And θ₆
Using the current position change ΔX ₆, ΔY₆And calculate
And the position change ΔX₆, ΔY₆Using P_FiveTo L₀
Estimated vehicle position P advanced this time₆′ (X₆', Y₆')of
Find coordinates (steps 112, 107 to 11 in FIG. 3)
0). Guess vehicle position P₆′ And vehicle direction θ₆Is vehicle position repair
Output to the main part 5d,₆Is the map drawing controller 5
e.

Next, the vehicle position correcting section 5d outputs the estimated vehicle
Position P₆'In the map data buffer memory 5a.
Map map by projection method with reference to stored road data
4. Search for switching candidate links in priority order (step 2 in FIG. 4).
01). Here, the road RD _mIs road RD_nAway from
As a result, the first candidate link LK_m3And the second candidate Rin
KLK_k3It is assumed that only. Next, repair the vehicle position
Since the correct part 5d has a plurality of matching candidates (step
(YES at 202, NO at 203), the first
Candidate link LK_m3And the second candidate link LK_k3About the car
Nodes on both sides are specified (step 000). this
In the same way as before, link LK_m3About the rear of the vehicle
Mode is N_m2And link LK_k3About the rear of the vehicle
Mode is N_k2Becomes Therefore, in the next step 206,
Two nodes N_m2, N_k1Are not the same in the coordinate comparison of
You. At this time, the vehicle position correction unit 5d
The vehicle position P₆'To the first candidate link L
K_m3To the final vehicle position P
₆(Step 210), and the determined vehicle position data is
Figure read control unit 5b, vehicle position / vehicle direction calculation unit 5
c, Output to the map drawing control unit 5e.

[0048] Thus, the navigation processing by the map read control unit 5b and a map drawing control unit 5e, the vehicle position mark is moved further on the road RD _m traveling. In the same manner, each time a pulse is output from the distance sensor 4 while the vehicle is running, the vehicle position mark on the screen is displayed on the road RD _m
Move up.

In the above embodiment, the criterion at step 208 in FIG.
Other relatively small angles, such as °.

[0050]

According to the present invention, the position change of the vehicle is calculated every time the vehicle travels a fixed distance, and the position change is added to the previously determined vehicle position to obtain the estimated vehicle position. For the estimated vehicle position, search for candidate links for matching by the projection method with reference to the road data in descending order of priority,
When one candidate link is found, the estimated vehicle position is projected onto the candidate link to determine the current determined vehicle position. When a plurality of candidate links are found, at least the highest priority candidate link and the priority priority When the second highest candidate link branches off from the same node at a predetermined small angle or less on the rear side of the vehicle, the estimated vehicle position is used as the current determined vehicle position, otherwise the highest priority candidate link is used. Because the estimated vehicle position is projected to the current determined vehicle position, when the vehicle travels on a road that branches at a relatively small angle, map matching is temporarily stopped and only dead reckoning navigation is used. Detect vehicle position,
After passing through the branching point, map matching by the projection method is restarted, so that it is possible to avoid the occurrence of a matching error that is likely to occur at the branching point due to the way of traveling of the vehicle, sensor error, road data error, etc. After passing through the location, the correct vehicle position correction on the running road can be resumed again.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of a vehicle-mounted navigator embodying a vehicle position correcting method according to the present invention.

FIG. 2 is an explanatory diagram illustrating an operation of a vehicle position correcting unit in FIG.

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

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

FIG. 5 is an explanatory diagram of a vehicle position correcting method according to the present invention.

FIG. 6 is an explanatory diagram of a general vehicle position detection method using dead reckoning navigation.

FIG. 7 is an explanatory diagram of map matching by a conventional projection method.

FIG. 8 is an explanatory diagram of map matching by a conventional projection method.

FIG. 9 is an explanatory diagram of map matching by a conventional projection method.

FIG. 10 is an explanatory diagram showing a problem of map matching by a conventional projection method.

[Explanation of symbols]

 Reference Signs List 1 CD-ROM 3 Relative direction sensor 4 Distance sensor 5 System controller 5c Vehicle position / vehicle direction calculation unit 5d Vehicle position correction unit 5e Map drawing control unit 6 Display device

Claims (1)

(57) [Claims] 1. A position change amount of a vehicle is calculated every time the vehicle travels a fixed distance, and a position change amount is added to a previously determined vehicle position to obtain an estimated vehicle position. The candidate links for matching by the projection method are searched in order of priority with reference to the data. If there is only one candidate link found, the estimated vehicle position is projected on the candidate link to determine the current confirmed vehicle position. When there are a plurality of links, at least when the candidate link having the highest priority and the candidate link having the second highest priority branch off from the same node at a predetermined small angle or less on the rear side of the vehicle, the estimated vehicle position remains unchanged. The current determined vehicle position; otherwise, the estimated vehicle position is projected on the candidate link having the highest priority to obtain the current determined vehicle position. Positive way.