JP2891813B2 - 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 obtained 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.

In the map data stored in the CD-ROM, a road is represented by a set of coordinates of vertices (nodes) expressed in latitude and longitude, and the drawing is performed by connecting the nodes sequentially with straight lines. . A part connecting two or more nodes is called a road link.

[0004] By the way, in-vehicle navigator of dead reckoning navigation
Is based on the output of the distance sensor and the relative direction sensor, for example.
The vehicle position is detected by the integration. Figure 5 shows dead reckoning
It is explanatory drawing which shows the vehicle position detection method. Distance sensor is car
Both have a certain unit distance L₀A pulse is output every time you drive
And the reference direction (θ = 0) is the positive direction of the X axis,
When the counterclockwise direction is set to + direction, after the previous correction
Vehicle position is point P₀(X ₀, Y₀) And the point P₀At
The vehicle direction (absolute direction) is θ₀, The unit distance L ₀Running
Output of the relative bearing sensor at the time₁Was
Then, the change in the vehicle position is ΔX = L₀・ Cos (θ₀+ Δθ₁) ΔY = L₀・ Sin (θ₀+ Δθ₁) And this point P₁Vehicle orientation θ₁And position coordinates (X
₁, Y₁) Is θ₁= Θ₀+ Δθ₁ ・ ・ (1) X₁= X₀+ ΔX = X₀+ L₀・ Cos θ₁ ・ ・ (2) Y₁= Y₀+ ΔY = Y₀+ L₀・ Sin θ₁ .. (3) can be calculated by vector synthesis. Yo
If you give the vehicle direction and position coordinates at the starting point,
After that, the vehicle moves₀Every time you run, (1)-
By repeating the calculation in (3), the vehicle position can be
System.

However, the distance sensor and the relative azimuth sensor are erroneous.
Due to the difference, the vehicle position detected by dead reckoning is
As you travel, errors accumulate and you move off the road.
U. For this reason, in-vehicle navigators use dead reckoning to detect
The vehicle position is checked against the road data in the map data
Is corrected above (map matching processing
Management). 6 to 8 show the theory of map matching by the projection method.
FIG. The vehicle position after the previous correction is point P_i-1(X
_i-1, Y_i-1) And the vehicle direction is θ_i-1It was
(Point P in FIG. 6)_i-1Is road RD_aIf not
Is shown). Point P_i-1More constant distance L₀(For example, 10
m) When running and a pulse is output from the distance sensor
Relative bearing is Δθ_iIf so, the primary vehicle position by dead reckoning
Placement point P_i′ (X _i', Y_i') And P_i′
θ_iIs given by Equations (1) to (3)._i= Θ_i-1+ Δθ_i X_i'= X_i-1+ L₀・ Cos θ_i Y_i'= Y_i-1+ L₀・ Sin θ_i Is required.

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 the vertical line within a certain distance. This
Here is Road RD_aUpper direction θ_a1Link LK_a1(node
N_a0And N_a1And the road RD_bUpper direction θ_b1No
Nk LK_b1(Node N_b0And N_b1). (B) Point P_i'From link LK_a1, LK_b1Hanging down
Line RL_ia, RL_ibThe shorter link and map the shorter link.
It is considered as a candidate for tuning. Here link LK_a1Becomes (C) And point P_i-1And point P_i′ Running trajectory SH
_iTo the perpendicular RL_iaPoint P in the direction of_i-1Is link LK_a1Above
Or link LK_a1Until it reaches the extension of
And point P_i-1And 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
Turn to find the point of movement, and calculate the corrected vehicle position P_i(X _i, Y
_i).

[0007] In addition, the vehicle direction of a modified vehicle position P _i is θ
_i will be left. If the corresponding link is not found in (a), the primary vehicle position P _i ′ is used as the corrected vehicle position P _i (X _i , Y _i ). Further, as shown in FIG.
When P _i-1 that it is last modified vehicle position is on the road RD _a is the moving point PT _i-1 is consistent with the point P _i-1. Also,
As shown in FIG. 8, a point P _i-1 if the vehicle has turned at an intersection, the primary vehicle position P _i 'modification is projected onto the road RD _a crossing the road RD _b in the map-matching the vehicle position P _i (X _i,
Y _i ).

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.

However, in the map matching based on the projection method as described above, as shown in FIG.
_c has been bent at the node N _c0, when the road RD _c substantially parallel to the road RD _d is present in the vicinity, the blind spot (DS references primary vehicle position detected by dead reckoning enclosed by oblique lines point 'becomes, in the step of the above (a), the point P _j' P _j) of the link LK _c0 sandwich the node N _c0 from LK
_Since no perpendicular line can be dropped on any of _c1 , while a perpendicular line RL _jd can be dropped on the link LK _d0 side of the road RD _d , the vehicle direction θ _j at the point P _j ′ and the link LK _d0
If the angle between the two is within a certain value and the length of the perpendicular RL _jd is within a certain value, the link LK _d0 of the road RD _d is a matching candidate.

For this reason, the corrected vehicle position P _j is determined by the link LK.
will fly on _d0, and later, the vehicle despite the fact that the vehicle is traveling on a road RD _c, vehicle position will be map-matching wrong on the road RD _d, moreover, then,
It becomes impossible to return to the correct road RD _c.

In view of this, as shown in FIG. 10, when performing map matching by the projection method, the links LK _c0 and L
K _C1 is extended by a predetermined length (see FIGS. 10A and 10B), and links LK _C0 and LK _C1 before the primary vehicle position P _j ′ detected by dead reckoning are extended are within a blind spot range. (D
(See S), the perpendiculars RL _j1 and RL _j2 can be lowered to the extended portions a and b at the point P _j ′. If the perpendicular RL _j1 is shorter, the link LK _c0 is connected. A proposal has been made by the inventor of the present application to prevent the occurrence of mismatching by making the corrected vehicle position P _{j + 1} on the extension of the _lik LK _{c0 as} a matching candidate (Japanese Patent Application No. 3-226170). No.).

[0012]

However, FIG.
The primary vehicle position P_j'Vehicle position
P_jIs wrong link LK_d0Can prevent it from coming on
The original link LK _C0, LK_C1(Extensions a and b
) Except for the position
Next primary vehicle position P as starting point_{j + 1}'Is the original phosphorus
KLK_C0, LK_C1Will come out of the way. This
, The primary vehicle position P_{j + 1}', Another link L
K_d0There was an attempt to match by projection
When the corrected vehicle position is incorrectly linked to link LK_d0I got on
(P in FIG. 10)_{j + 1}See), risk of mismatch
was there.

Further, since the corrected vehicle position P _j with respect to the primary vehicle position P _j ′ comes to an extension of the links LK _C0 , LK _C1 , the vehicle position mark displayed on the screen is displayed as off the road, There was a problem that it felt unnatural.

Accordingly, an object of the present invention is to provide a vehicle position correcting method capable of reliably avoiding a map matching error and preventing a vehicle position mark from deviating from a road.

[0015]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for determining a primary vehicle position by dead reckoning navigation every time a vehicle travels a predetermined distance, and a method of extending a link in road data by a predetermined length. Means for searching for a link from which a perpendicular line can be dropped from the primary vehicle position, means for performing matching by projection on one link satisfying a predetermined condition from the searched links, and obtaining a secondary vehicle position. This is achieved by means for setting the corrected vehicle position as it is when the next vehicle position is on the original link, and as the corrected vehicle position when the secondary vehicle position is on the extension of the original link. .

[0016]

According to the present invention, the primary vehicle position is obtained by dead reckoning navigation every time the vehicle travels a fixed distance, and the vertical line can be lowered from the primary vehicle position while extending the link in the road data by a predetermined length. Searching for links, performing a matching by a projection method on one link satisfying a predetermined condition from the searched links to obtain a secondary vehicle position,
When the secondary vehicle position is on the original link, the corrected vehicle position is used as it is. When the secondary vehicle position is on the extension of the original link, the end of the original link is used as the corrected vehicle position. Accordingly, even if the primary vehicle position comes to a curved portion of the road, the vehicle position can be reliably corrected on the correct road without making a mistake in the matching target road, and the vehicle position mark does not deviate from the road. Like so
It is possible to prevent an unnatural display state from occurring.

[0017]

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 2 denotes an operation panel. Left, right, up, and down scroll keys for scrolling the map with respect to the 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, departure point data or corrected vehicle position data is input from a vehicle position / vehicle direction calculation unit or a vehicle position correction unit to be described later, and map data around the departure point or the vehicle position is stored in the map data buffer memory 5a from the CD-ROM 1. A map reading control unit 5c to be read and a vehicle position / vehicle direction calculating unit 5c are used to calculate the current position (longitude and latitude) of the vehicle by dead reckoning using the signals input from the relative direction sensor 3 and the distance sensor 4. The vehicle direction is calculated, and primary vehicle position data and vehicle direction data are output. 5d is a map data buffer memory 5a based on primary vehicle position data.
A vehicle position correction unit that corrects a vehicle position by map matching based on a projection method with reference to road data in the map data read out, a driving data memory 5e storing a previous corrected vehicle position, and a map data buffer 5f. The map data around the vehicle position is read from the memory 5a and output to a display device to draw a map, and the corrected vehicle position data input from the vehicle position correction unit 5d and the vehicle direction data input from the vehicle position / vehicle direction calculation unit 5c. Is output to the display device 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. 2 is a first flowchart showing the operation of the system controller 5, FIG. 3 is a second flowchart showing the operation of the system controller 5, and FIG. 4 is an explanatory diagram of a vehicle position correcting method. Description will be made with reference to the drawings.

In accordance with the map selection operation by the driver, the map reading control unit 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, and performs map drawing control. The unit 5f reads out 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 1
It is assumed that the image is drawn on the screen 0.

When the driver performs an operation of setting (X ₀ , Y ₀ ) as the position coordinates of the departure place and θ ₀ as the vehicle azimuth (the absolute azimuth of the vehicle traveling direction) on the operation panel 2, the vehicle position P at the departure place is obtained. as _{0 (X 0, Y 0)} , also has theta ₀ as the vehicle orientation at P ₀ is initialized like a vehicle position and vehicle direction calculation section 5c (step 101 to 104 in FIG. 2). Further, the map drawing control unit 5f outputs the 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 directs the vehicle to a predetermined location on the map screen. and to display the vehicle position mark (step 105), the vehicle position correcting unit 5d is registered in the running data memory 5e to P ₀ as last modified vehicle position data S (step 106).

When the vehicle starts running, a certain distance L
₀(In this example, it is 10 m as an example.)
Then, the distance sensor 4 outputs a pulse. Distance sensor 4
When the first pulse is input, the vehicle position and direction are calculated
The unit 5c receives the relative direction signal Δθ from the relative direction sensor 3.₁Enter
Force (steps 107-109), set unit distance L₀,
Departure point P₀Modified vehicle position coordinates S = (X₀, Y₀)
And vehicle direction θ₀, And by dead reckoning, θ₁= Θ₀+ Δθ₁ ΔX = L₀・ Cos θ₁ ΔY = L₀・ Sin θ₁ X₁'= X₀+ ΔXY₁'= Y₀+ ΔY is calculated and P₀To L₀The primary vehicle that just advanced
Position P₁′ (X₁', Y ₁') And the vehicle orientation θ₁
Are obtained (steps 110 and 111). Primary vehicle position P
₁′ And vehicle direction θ₁Data is output to the vehicle position correction unit 5d.
Force, vehicle orientation θ₁To the map drawing control unit 5f
Is output.

Subsequently, the vehicle position correcting section 5d operates the primary vehicle
Position P₁′ For the vehicle position by map matching
Make corrections. That is, first, the map data buffer memory 5
a with reference to the road data stored in the
Do not extend the link by a first fixed length (eg, 30m)
Point P₁′ And a vertical line within the second fixed length
And the vehicle direction θ₁And the angle between the link and
Search for links that are within a certain value (step in FIG. 3)
201). Here is road RD_eLink LK above _e1(No
De N_e0And N_e1And the road RD_fLink LK above
_f1(Node N_f0And N_f1). In addition, here
Then point P₁'Is the link LK_e1of
Non-extended part and link LK_f1Shall come to the non-extended part of
You.

Next, since a link from which the perpendicular can be dropped has been extracted (YES in step 202), the point P ₁ '
Perpendiculars RL _1e , RL dropped to links LK _e1 , LK _f1 from
The length of _1f is obtained, and the shorter link is set as a matching candidate (step 203). Here, the link is LK _e1 .

Next, the vehicle position correcting section 5d stores the last corrected vehicle position S stored in the traveling data memory 5e.
Travel locus SH = P ₀ and the current primary vehicle position P ₁ ′
₁ in the direction of the perpendicular RL _1e until the point P ₀ is on the link LK _e1 or on an extension of the link LK _e1 ,
The moving points PT ₀ and PT ₁ ′ of ₀ and P ₁ ′ are obtained, and the moving points are further rotated around the point PT ₀ until PT ₁ ′ is on the link LK _e1 or on an extension of the link LK _e1. determined, the secondary vehicle position P ₁ "and (step 204). Then, the vehicle position correcting unit 5d secondary vehicle position P _1" or present on the original link LK _e1 (non-extension of the link) , It is determined whether it exists on the extension (step 20).
5) Here, _{assuming that} the secondary vehicle position P ₁ ″ is present on the original link LK _e1 , the secondary vehicle position P ₁ ″ is set as the corrected vehicle position P ₁ (X ₁ , Y ₁ ) (step 206).
Vehicle position correcting unit 5d, the map read control unit 5b correction vehicle position P _1, the vehicle position and vehicle direction calculation unit 5c, and outputs to the map drawing control unit 5f, the traveling data memory 5
and S = P ₁ of e (step 207).

When a predetermined link cannot be extracted in step 201, the vehicle position correcting section 5d sets the primary vehicle position P ₁ ′ as the corrected vehicle position P ₁ (steps 202 and 208).

The map reading control unit 5b, based on the current corrected vehicle position data input from the vehicle position correcting 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 5f outputs the current corrected 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 5f transmits 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 and output to the display device 6 to change the display map (the above, the navigation processing, step 11 in FIG. 2)
2).

When the second pulse is input from the distance sensor 4, the vehicle position / vehicle azimuth calculating section 5c performs the dead reckoning navigation with the previous determined vehicle position P ₁ as a starting point in the same manner as described above. ₂ ′ position coordinates (X ₂ ′, Y
₂ ′) and the vehicle direction θ ₂ , and outputs the primary vehicle position data and the vehicle direction data to the vehicle position correction unit 5d, and outputs the vehicle direction data to the map drawing control unit 5f (step 11).
3, 108-111). Then, the vehicle position correction unit 5d
From the current primary vehicle position P ₂ ′ in the same manner as described above.
Search for matching candidate links (step 20 in FIG. 3)
1). And even matching candidate has become a link LK _e1 on the road RD _e here.

Next, the vehicle position correcting section 5d determines the last corrected vehicle position S stored in the traveling data memory 5e.
= P ₁ and the traveling locus SH connecting this primary vehicle position P ₂ '
The point P ₁ toward ₂ to link LK _e1 moves parallel until the upper link LK _e1 (or an extension of the link LK _e1), 'moving point PT ₁ of the PT _2' points P ₁ and P ₂ a Asked,
Furthermore, PT ₂ 'around the point PT ₁ link LK rotational movement to seek moving point until the _e1 upper (or an extension of the link LK _e1), the secondary vehicle position P ₂ "(Step 2
02-204). Subsequently, the vehicle position correction unit 5d determines whether the secondary vehicle position P ₂ ″ exists on the original link LK _e1 (non-extended portion of the link) or on the extended portion (step 205). Again, the original link LK _e1
The secondary vehicle position P ₂ ″ is set as the corrected vehicle position P ₂ (X ₂ , Y ₂ ) (step 2
06). Vehicle position correcting unit 5d outputs the corrected vehicle position P ₂ to the map read control unit 5b and a map drawing control unit 5f, and S = P ₂ of the running data memory 5e (Step 207).

The map reading control unit 5b, based on the current corrected vehicle position data input from the vehicle position correcting 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. Further, the map drawing control unit 5f outputs the current corrected vehicle position data (P ₂ ) and the vehicle direction data (θ ₂ ) previously input from the vehicle position / vehicle direction calculation unit 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 5f transmits 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 and read out to the display device 6 to change the display map (step 112 in FIG. 2).

Corrected vehicle position P_TwoRoad RD at the end of_eBut no
De N_e1Link LK_e1From LK_e2Bent to
The third pulse is input from the distance sensor 4
The primary vehicle position when_Three', P_Three'
Directly link LK _e1And LK_e2Drop the perpendicular to
Can't, but link LK_e1Link with extension a of
LK_e2Perpendicular RL to the extension b of_30e,RL_31eTake down
Can be. In addition, road RD_fSide link LK_f1Also hanging
Line RL_3fCan be taken down. Therefore, the perpendicular RL_30e,
RL_31e,RL_3fAre within the second fixed length
Yes and vehicle direction θ_ThreeAnd each link LK_e1, LK_e2,
LK_f1If the angle between the
The two-position correcting unit 5d sets the link L in step 201 of FIG.
K_e1, LK_e2, LK_f1Is extracted.

Next, the vehicle position correcting section 5d operates the link LK.
_e1, LK_e2, LK_f1Perpendicular RL from inside_30e,RL_31e,RL
_3fFind the one with the shortest length and make it a matching candidate
(Steps 202 and 203). Here, link LK_e1
It is assumed that Next, the vehicle position correction unit 5d
Previous corrected vehicle position stored in the travel data memory 5e
S = P_TwoAnd the current primary vehicle position P_Three′
Locus SH_ThreeTo the perpendicular RL _30ePoint P in the direction of_TwoIs link LK
_e1Up (or link LK_e1Parallel to the extension of
Move to point P_TwoAnd P_Three'Movement point PT_TwoAnd PT_Three′
Required, and then PT_TwoPT around_Three'Is the link LK_e1
Up (or link LK_e1Rotation on the extension of
Move to obtain the moving point, and the secondary vehicle position P_Three"
204).

Subsequently, the vehicle position correcting section 5d determines that the secondary vehicle position P ₃ ″ is the original link LK _e1 (the non-extended portion of the link).
(Step 205). Here, since present on the extended portion a, the vehicle position correcting unit 5d of the node N _e0 and N _e1 is an end of the original link LK _e1, the coordinates of the node N _e1 closer to P ₃ " The corrected vehicle position P _{3 is set to} (X ₃ , Y ₃ ) (step 209), and the corrected vehicle position P ₃ is output to the map reading control unit 5b and the map drawing control unit 5f, and S = and P ₃ (step 207).

[0036] Thus, the subsequent, in the display control of the vehicle position mark by the map drawing control unit 5f, since the vehicle position mark is moved to the position of the node N _e1, not only do not have to fly on the road RD _f by mistake, correct it without departing from the road RD _e, it does not occur unnatural (step 11 in FIG. 2
2).

Thereafter, the fourth pulse from the distance sensor 4
Is input, the vehicle position / vehicle direction calculation unit 5c
Times corrected vehicle position P_ThreePrimary vehicle position by dead reckoning navigation based on
P_Four′ And the vehicle direction θ_FourIs calculated (Figure
2 steps 113, 108-111). At this time, guess
The origin of navigation is node N_e1Therefore, the primary vehicle position P
_Four'Is the link LK_e1, LK_e2Can't deviate significantly from
No. Next, the vehicle position correction unit 5d determines the point P_FourFrom '
Find a link that can be removed (step 20 in FIG. 3)
1). At this time, P_Four'From the link LK_e1Non
A vertical line can be dropped on both the extension and extension a.
Can't, but link LK_e2Perpendicular RL directly to _4eTake down
And link LK_f1Also perpendicular RL_4fLower
be able to. Therefore, the perpendicular RL_4e,RL_4fThe length of
The deviation is also within the second fixed length, and the vehicle direction θ_Four
And each link LK_e2, LK_f1Angle is constant
If the value is within the range, the vehicle position correction unit 5d proceeds to step 20.
Link LK at 1_e2, LK_f1Is extracted.

Next, the vehicle position correcting section 5d sets the link LK.
_e2, seek those perpendicular RL _4e, the shorter the length of the RL _4f from the LK _f1, the matching candidate (step 20
2, 203). Here, as described above, since the primary vehicle position P ₄ ′ is near the link LK _e2 , the matching candidate is correctly set to the link LK _e2 . Then, the vehicle position correcting unit 5d, the running locus SH ₄ connecting the S = P ₃ is a last modified vehicle position stored in the driving data memory 5e the current primary vehicle position P ₄ 'in the direction of the perpendicular line RL _4e the point P ₃ is moved in parallel until the upper link LK _e2 (or an extension of the link LK _e2), obtains a 'and moving point PT ₃ of PT _4' points P ₃ and P _4, further point PT ₃ PT in the center
Rotational movement is performed until ₄ ′ is on the link LK _e2 (or on an extension of the link LK _e2 ) to obtain a moving point, which is set as the secondary vehicle position P ₄ ″ (step 204).

Subsequently, the vehicle position correcting section 5d determines that the secondary vehicle position P ₄ ″ is the original link LK _e2 (the non-extended portion of the link).
(Step 205). Here, since it exists on the original link LK _e2 , the corrected vehicle position P ₄ (X ₄ ,
Y ₄ ) (step 206). Vehicle position correction unit 5d
Outputs the corrected vehicle position P ₄ to the map read control unit 5b and a map drawing control unit 5f, and S = P ₄ of the traveling data memory 5e (Step 207).

[0040] Thus, the subsequent, in the display control of the vehicle mark by the map drawing control unit 5f, correctly, to move along the road RD _e to curve the node N _e1 (step 112 in FIG. 2).

Next, the fifth pulse from the distance sensor 4 is
When input, calculated by vehicle position / vehicle direction calculator 5c
Primary vehicle position P_Four', The vehicle position correction unit 5d
Can drop a vertical line within the first fixed length,
One, vehicle direction θ_FiveSearch for links whose angle difference with
Suddenly, link LK_f1Is far away, so Rin
KLK_e2Extracted as matching candidates (step
Steps 113 and 108 to 111 in FIG.
203). And the vehicle position is the link LK_e2Upper point P_Five
(Steps 204, 205, 206). Yo
Therefore, the vehicle position mark is correct by the map drawing control unit 5f.
Road RD currently running_eLink LK _e2Moving table up
(Step 112 in FIG. 2).

[0042] After that, as long as the vehicle is traveling on a road RD _e, even if there is bent in the middle, in the same manner as described above,
Vehicle position by the map matching, continues to be properly corrected onto the road RD _e.

In the above-described embodiment, the link having the shortest perpendicular is selected as the matching candidate from the links extracted in step 201 in FIG. 3, but the angle between the vehicle direction and the link is the smallest. These may be used as matching candidates. The length of the extension of the link when determining whether or not the vertical line can be lowered in step 201 is not necessarily 3
The length is not limited to 0 m and may be another length such as 20 m or 40 m. Further, the unit traveling distance L _{0 at} which the distance sensor outputs a pulse may be changed to a length other than 10 m, and the length of extending the link when determining whether it is possible to drop the perpendicular in step 201 is as follows. , May be set as appropriate according to the unit traveling distance L ₀ .

[0044]

According to the present invention, the primary vehicle position is determined by dead reckoning navigation every time the vehicle travels a fixed distance, and the vertical line is lowered from the primary vehicle position while extending the link in the road data by a predetermined length. A search is made for a link that can be used, a matching is performed by a projection method on one of the links found that satisfies a predetermined condition, a secondary vehicle position is obtained, and the secondary vehicle position exists on the original link. When the secondary vehicle position is on the extension of the original link, the end of the original link is used as the modified vehicle position, so that the primary vehicle position is a curved part of the road. The vehicle position can be corrected on the correct road without mistake in the matching target road even if the vehicle comes in, and the vehicle position mark does not deviate from the road. , It is possible to prevent the occurrence of unnatural display state.

[Brief description of the drawings]

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

FIG. 2 is a first diagram illustrating the operation of the system controller of FIG. 1;
It is a flowchart of.

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

FIG. 4 is an explanatory diagram of a vehicle position correcting method according to the present invention.

FIG. 5 is an explanatory diagram of a general vehicle position detection method using dead reckoning navigation.

FIG. 6 is an explanatory diagram of map matching by a conventional projection method.

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 showing a problem of map matching by a conventional projection method.

FIG. 10 is an explanatory diagram showing a problem of map matching by a conventional improved 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 Travel data memory 5f Map drawing control unit 6 Display device

Claims (1)

(57) [Claims] 1. Every time a vehicle travels a certain distance, a primary vehicle position is obtained by dead reckoning navigation, and while a link in the road data is extended by a predetermined length, a link that can drop a vertical line from the primary vehicle position is searched for. From the found links, one of the links that satisfies the predetermined condition is subjected to the matching by the projection method, and the secondary vehicle position is obtained. If the secondary vehicle position exists on the original link, the secondary vehicle position is used as it is as the corrected vehicle position. And correcting the end of the original link as the corrected vehicle position when the secondary vehicle position is on an extension of the original link.