JPH06331373A - Method of detecting vehicle position - Google Patents

Abstract

PURPOSE:To enable the detecting of the position of a vehicle even when only two satellites exist from which satellite radio waves can be received at the vehicle. CONSTITUTION:A position measuring section 8b of a GPS receiver 5 performs a one-dimensional position measurement using the newest alititude data determined to determine a line of existence of a vehicle on a fixed spherical surface by a value with the alititude known when the number of satellites to be captured with a demodulation section 7 is down to only two to disable three- dimensional and two-dimensional position measurements and outputs the results to a map matching section 13. The map matching section 13 calculates an intersection between a road where the vehicle runs or a road linked to the road and a line of existence of the vehicle near the position of the vehicle using a road data of a CD-ROM 1 to determine the new position of the vehicle. A map image drawing section 12 controls a reading control section 15 based on the position of the vehicle to read out a map by one portion of screen centered on the position of the vehicle from among maps drawn in a video RAM 14. A vehicle position mark is synthesized with a synthesizing section 17 centered on the map read out to be shown on a CRT display device 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle position detecting method, and more particularly to a vehicle position detecting method for improving a vehicle position detecting rate in an in-vehicle navigation device which detects a vehicle position using a GPS receiver. .

[0002]

2. Description of the Related Art There is a vehicle-mounted navigation device that guides a vehicle so that a driver can easily reach a desired destination. In this vehicle-mounted navigation device, a CD-ROM is detected by detecting the position and direction of the vehicle while traveling.
Read the map data around the vehicle position from the V-RAM
A map image is drawn on the map image, and a vehicle position mark is drawn at a position corresponding to the current position on the map image in a direction corresponding to the vehicle traveling direction. The CRT is performed while converting the V-RAM image into a video signal. Output to a display device and display on the screen. Then, as the current position changes with the movement of the vehicle, the map on the screen is fixed and only the vehicle position mark moves, or, conversely, the vehicle position mark is fixed at the center of the screen and the map is scrolled, The map information around the vehicle position is always visible at a glance.

The map stored in the CD-ROM is managed as a map leaf which is divided into regions of a longitude width and a latitude width of which the north is facing up and the size is appropriate according to the scale level, like a map book. And each leaf is further divided into four data units. The map data includes (1) background layer for displaying roads, parks, rivers, etc. (2) character / symbol layer for displaying municipalities, road names, map symbols, etc. (3) map matching, etc. It is composed of road layers. The map image is drawn using a background layer, a character / symbol layer, and the like. In the map data,
A road is defined by a set of vertices (nodes), and a part connecting two vertices is called a link.

The road layer included in the map data is shown in FIG.
It has the data structure shown in. Of these, road list R
DLT is the number of all nodes on the road, the number on the node list NDLT of the nodes that make up the road, the type of road (national road, highway, other), road number (road name)
Etc. data is included. Also, the intersection configuration node C
The RLT is, for each intersection on the map, a set of numbers on the node list NDLT of the other end node (intersection composing node) forming a link with the intersection.
LT is a list of all the nodes that make up the road. For each node, position information (longitude, latitude), an intersection identification flag indicating whether or not the node is an intersection, the altitude (altitude) of the node, and the node are If it is an intersection, it is composed of a pointer or the like that points to the position on the corresponding intersection constituent node list CRLT, and if it is not an intersection, it points to the position on the road list RDLT to which the node belongs.

A vehicle position detection method in an in-vehicle navigation system is to detect a vehicle direction and a traveling distance by using a direction sensor and a distance sensor while traveling, and sequentially accumulate a position change amount every time the vehicle travels a certain distance. GPS which calculates the absolute position by the self-contained navigation required and the radio waves from multiple Earth-orbiting satellites (GPS satellites) are caught and the principle of triangulation is calculated.
There is satellite navigation (GPS; Global Positioning System).

The former self-contained navigation can detect the vehicle position at low cost, but has a drawback that sensor errors accumulate when the mileage becomes long or the meandering operation continues. Also, it cannot be retrofitted to the vehicle. On the other hand, the latter vehicle position detection error by GPS always stays within a certain range, and retrofitting to a vehicle can be easily performed. And
It has been in the spotlight in recent years because the price has been reduced due to mass production.

Explaining the principle of GPS satellite navigation, a plurality of satellites (GPS
A satellite), and a navigation message (orbit information,
A PRN code (C / A code or P code) that is different for each satellite and a calendar is transmitted by spread spectrum modulation. A satellite signal from each of these satellites is received by a GPS receiver equipped in the vehicle-mounted navigation device, despread to obtain a PRN code, and a navigation message is decoded. Each satellite has a built-in atomic clock that is synchronized with each other.
The PRN code indicates the satellite transmission time. The GPS receiver measures the time required for the satellite signal to reach the vehicle from each satellite using the PRN code, using the clock built in the GPS receiver, multiplies the speed of light, and performs a predetermined correction using the navigation message. Thus, the distance between the satellite and the vehicle is calculated for a predetermined number of satellites (usually four). Since the position of each satellite can be calculated from the navigation message, the vehicle position is calculated with high accuracy by the principle of triangulation using the satellite position data and the satellite-vehicle distance data.

GPS satellite navigation uses three-dimensional positioning (eg,
(Longitude, latitude, altitude) is the basic system, but if the altitude is known, such as at sea, if the altitude data is included in the map data and the altitude data can be used, If the altitude is known, such as when the altitude is obtained by the three-dimensional positioning, the longitude and latitude can be measured by the two-dimensional positioning. Figure 10: GPS receiver clock and GP
3 if the atomic clocks of S satellites are perfectly synchronized
It is explanatory drawing of two-dimensional positioning and two-dimensional positioning.

First, the three-dimensional positioning will be described.
Observable from a certain observation point in the appropriate 3D coordinate system
The positions of the three GPS satellites STL1 to STL3 are P₁~ P
₃, The distance between each GPS satellite STL1-STL3 and the vehicle
R₁~ R₃When, P ₁~ P₃To radius R₁
~ R₃Draw spherical surfaces CUB1 to CUB3 of
Circle CIL where CUB2 intersects with₁₂And the spherical CUB3 intersection
Three-dimensional coordinate values of S and Q are obtained. One of S and Q
The true position of the station and the false position of the other
The position of is far from the value considered as the observation point.
And can be easily excluded (in outer space far from Earth)
It That is, three-dimensional positioning has three unknowns related to the observation point.
Sometimes (eg longitude, latitude, altitude), 3 GPS
Receives satellite signals from satellites and locates these three satellites
And the distance to the observation point, three simultaneous 3D coordinates
The equation is set up and the solution is sought.

Two-dimensional positioning will now be described. Two GPS satellites STL1 capable of observing from a certain observation point whose plane including itself (including a spherical surface here) is known in advance in an appropriate three-dimensional coordinate system. And the position of STL2 is P ₁ and P
_2, when the distance between each GPS satellite STL1 and STL2 and the vehicle becomes R ₁ and R _2, each radius R from P ₁ and P ₂
Draw spherical spheres CUB1 and CUB2 of ₁ and R ₂ ,
The coordinate value of the point (there are two, but the distinction between true and false is easy) where the circle CIL ₁₂ where 1 and CUB2 intersect and a known plane intersect is obtained. That is, two-dimensional positioning is performed, for example, when there are two unknowns regarding the observation point (for example, longitude and latitude),
Using the position of one GPS satellite and the distance from these two GPS satellites to the observation point, two simultaneous equations of three-dimensional coordinates are established, and one equation regarding the known value (eg altitude) of the observation point is established. , To solve three simultaneous equations combined with the previous two simultaneous equations.

However, in reality, the GPS receiver clock and G
Since there is a time difference between the time clock and the atomic clock of the PS satellite, this time difference must also be included in the unknown number.
In one three-dimensional positioning, satellite signals are received from four GPS satellites, the positions of these four GPS satellites and the distances to the observation points are obtained, four simultaneous equations are set up, and a solution is obtained. In positioning, satellite signals are received from three GPS satellites, the positions of these three GPS satellites and the distances to the observation points are calculated, three simultaneous equations are established, and one equation regarding the known values of the observation points is established. It tries to solve four simultaneous equations including the three simultaneous equations.

That is, in the three-dimensional positioning in the X, Y, Z Cartesian coordinate system with the earth center as the origin, the position P _{0 of the} observation point is
(X ₀ , y ₀ , z ₀ ), and the position P _i of the i (i = 1, 2, 3, 4) -th GPS satellite is (x _i , y _i , z _i ), i
Assuming that the arrival time of the radio wave from the GPS satellite is τ _i and the time error is δt, {(x _i −x ₀ ) ² + (y _i −y ₀ ) ² + (z _i −
z ₀ ) ² } ^1/2 = c · (τ _i + δt) holds, and c · τ _i = R _i , c · δt = s, then {(x _i −x ₀ ) ² + (y _{i ^{-y 0) 2 + (z i}} -z 0) 2} becomes _{^{1/2 -s = R i ··· (1}} ). Since the equation (1) holds for four GPS satellites, the four unknowns x ₀ , y ₀ , z ₀ , and s are obtained to obtain the highly accurate observation point position x ₀ , y with the time error corrected.
₀ and z ₀ are obtained. If a predetermined coordinate conversion is performed, the longitude, latitude and altitude can be obtained.

In the two-dimensional positioning when the altitude h of the observation point is known in advance, the formula (1) is established for three GPS satellites (provided that i = 1, 2, 3). By combining the following equations regarding the altitude h, (x ₀ ² + y ₀ ² + z ₀ ² ) ^1/2 = h (2), the four unknowns x ₀ , y ₀ , z ₀ , and s are obtained. High-precision position x ₀ with corrected time error,
If y ₀ and z ₀ are obtained and a predetermined coordinate conversion is performed, the longitude,
The latitude is obtained.

When there are four or more satellites capable of receiving satellite radio waves from the vehicle, the GPS receiver in the vehicle-mounted navigation device selects four satellites (satellite constellation that minimizes the DOP value) out of these four satellites. Three-dimensional positioning is performed and the vehicle position (longitude, latitude) is detected. If there are only three satellites that can receive satellite radio waves from the vehicle, such as when the satellite radio waves are blocked by obstacles such as buildings, the altitude has been sought by three-dimensional positioning in the past,
When the altitude data is included in the map data, the altitude is known and the vehicle position is detected by two-dimensional positioning.

[0015]

However, in the conventional GPS satellite navigation, the vehicle position is detected in principle when there are only two satellites capable of receiving satellite radio waves from the vehicle, such as traveling in a building street. Can not do.
In this case, if the vehicle-mounted navigation device is equipped with a distance sensor and a direction sensor, it is possible to switch to self-contained navigation and continue detecting the vehicle position. ,
Although the vehicle is traveling, there is a problem that the vehicle position mark is fixed on the map image and the accurate current position cannot be known.

It is therefore an object of the present invention to provide a vehicle position detecting method capable of detecting the vehicle position even when there are only two satellites capable of receiving satellite radio waves from the vehicle.

[0017]

SUMMARY OF THE INVENTION In the present invention, the above object is to provide a map information storage means for storing map data including road data and three-dimensional positioning during positioning by satellite navigation.
When neither one of the two-dimensional positioning is possible, one-dimensional positioning is performed using known altitude data, and means for determining the existence line of the vehicle on a spherical surface where the altitude is constant at the known value when viewed from the center of the earth. , Means for obtaining a new vehicle position by referring to the road data and calculating the intersection of the road on which the vehicle position obtained last time or the road connected to the road and the existing line in the vicinity of the vehicle position are calculated. It is achieved by providing.

[0018]

According to the present invention, when neither three-dimensional positioning nor two-dimensional positioning is possible during positioning of a vehicle position by satellite navigation, one-dimensional positioning is performed using known altitude data,
Find the line of existence of the vehicle on a spherical surface where the altitude is constant with the known value when viewed from the center of the earth, refer to the road data, and connect to the road on which the previously determined vehicle position is on or to the road. A new vehicle position is obtained by calculating the intersection of the road and the existing line near the vehicle position. This allows the vehicle position to be detected even when there are only two satellites that can receive satellite radio waves from the vehicle, such as when traveling in a building street, and greatly improves the vehicle position detection rate by satellite navigation. be able to.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram of a vehicle-mounted navigation device embodying a vehicle position detecting method according to the present invention. In the figure, 1 is a CD-ROM that serves as map data storage means,
Reference numeral 2 is an operation panel, which is provided with a map search key, an enlargement / reduction key and the like. A CRT display device 3 inputs a video signal and displays a map on the screen together with a vehicle position mark and the like. 4 is a multi-beam antenna that catches satellite radio waves from a plurality of GPS satellites, 5 is a satellite signal that is received by the multi-beam antenna, and vehicle position (absolute coordinates consisting of longitude and latitude), vehicle direction, and It is a GPS receiver that detects vehicle speed and the like.

When there are four or more GPS satellites capable of receiving satellite radio waves in the sky, the GPS receiver 5 performs three-dimensional positioning to detect the vehicle position, and three GPS satellites capable of receiving satellite radio waves in the sky. When present, two-dimensional positioning is performed to detect the vehicle position. If there are only two GPS satellites that can receive satellite radio waves in the sky, it will be described later 1
Dimensional positioning is performed to find the line of existence of the vehicle position on a spherical surface of constant altitude.

Of the GPS receivers 5, 6 is a receiver for performing high frequency amplification, frequency conversion, and intermediate frequency amplification on the satellite signals received by the multi-beam antenna 4, and 7 is a plurality of satellite signals at the same time. A multi-channel demodulation unit for demodulating PRN code by spectrum despreading, measuring pseudo-range and Doppler amount, decoding navigation message, etc.
Reference numeral 8 denotes a processing unit having a microcomputer configuration for calculating a vehicle position, a vehicle direction, a vehicle speed, etc. Among these, 8a stores a navigation message and the latest position data (longitude, latitude, altitude) stored. This is a buffer memory and is backed up by a battery so that data can be saved even after the power is turned off. 8b identifies the satellite position by referring to the navigation message, controls the demodulator 7 to capture a large number of satellites that can receive satellite signals (the maximum number of satellites that can be captured is the number of channels of the demodulator 7). The number of fixed satellites is six (here, six), and a positioning unit that inputs the pseudo range signals for a plurality of predetermined satellites from the demodulation unit 7 and measures the current position by satellite navigation. A demodulation unit 7 inputs Doppler amount signals for a plurality of predetermined satellites, and a positioning unit 8b inputs satellite positions and measured current position data, and an azimuth vector (direction represents azimuth, size represents speed). Two
This is a direction vector calculation unit for obtaining a dimensional vector).

When the demodulating unit 7 can catch satellite signals from four or more satellites, the positioning unit 8b uses three satellite groups having the smallest DOP value (usually PDOP value) to generate 3 satellites.
If the satellite signal for only three satellites can be obtained by obtaining the longitude, latitude, and altitude of the vehicle current position by three-dimensional positioning, the altitude data obtained by the latest three-dimensional positioning is used to determine the vehicle current position by two-dimensional positioning. Find the longitude and latitude. In addition, the demodulation unit 7
If you can catch satellite signals from only two satellites,
By using the altitude data obtained by the latest three-dimensional positioning, the existing line of the vehicle current position on the spherical surface having a constant altitude is obtained by the one-dimensional positioning.

FIG. 2 is a diagram for explaining the principle of one-dimensional positioning. In a suitable three-dimensional coordinate system, the position of one GPS satellite STL1 that can be observed from a certain observation point whose plane including itself (here, the distance from the center of the earth = spherical surface with a constant height h) is known in advance. Is P ₁ and the distance between the GPS satellite STL1 and the vehicle is R ₁ , a spherical surface C having a radius R ₁ from P ₁
UB1 is drawn, and a circle CIL ₁₂ where the spherical surface CUB1 intersects with a known plane CUB2 is obtained. The circle CIL ₁₂ is the existence line on which the observation point exists. In the present embodiment, in order to facilitate the handling, a spherical surface CUB3 having a constant radius r (r is a short distance such as 0.5 km or 1 km) centered on the present location Q detected most recently in the past is drawn, and the circle CIL is drawn. 2 intersect with ₁₂
The points A and B are obtained, and the straight line LN connecting A and B is set as the existence line approximated to the circle CIL ₁₂ . Even if the existence line is linearly approximated in this way, there is no practical problem because the circle CIL ₁₂ is extremely large.

That is, the one-dimensional positioning is carried out when one unknown GP is associated with an observation point (for example, longitude and latitude) and one GP.
Using the position of the S satellite and the distance from this GPS satellite to the observation point, one equation of three-dimensional coordinates is made,
One equation concerning a known value (for example, altitude) of the observation point is established, one equation representing a range of a certain distance from the position most recently measured in the past is established, and three simultaneous equations including the above equation are solved. Is to find a relational expression near the observation point between two unknowns.

However, in reality, the GPS receiver clock and G
Since there is a time difference between the time clock and the atomic clock of the PS satellite, this time difference must also be included in the unknown number.
In one-dimensional one-time positioning, satellite signals are received from two GPS satellites, the positions of these two GPS satellites and the distances to the observation points are obtained to establish two simultaneous equations, and the known values of the observation points (for example, Altitude), one equation representing the range of a certain distance from the position most recently measured in the past, and four simultaneous equations combined with the previous equation are solved. The relational expression near the observation point between two unknowns is calculated.

That is, in one-dimensional positioning in the X, Y, Z orthogonal coordinate system with the earth center as the origin, the position P of the observation point is (x ₀ , y ₀ , z ₀ ), i-th (i = 1). , 2) GPS
The satellite position P _i is (x _i , y _i , z _i ), i-th GP
Assuming that the arrival time of the radio wave from the S satellite is τ _i and the time error is δt, {(x _i −x ₀ ) ² + (y _i −y ₀ ) ² + (z _i −
z ₀ ) ² } ^1/2 = c · (τ _i + δt) holds, and c · τ _i = R _i , c · δt = s, then {(x _i −x ₀ ) ² + (y _{i ^{-y 0) 2 + (z i}} -z 0) becomes _{^{2} 1/2 -s = R i ···}} (3). Equation (3) holds for two GPS satellites.
From the following equation regarding the altitude h, (x ₀ ² + y ₀ ² + z ₀ ² ) ^1/2 = h (4), and the position Q (x _q , y _q , z _q ) that was most recently measured the following equation representing a range of constant distance r, a ^{_{{(x q -x 0) 2}} + (y q -y 0) 2 + (z q -z 0) 2} 1/2 = r ··· (5) Solve the four simultaneous simultaneous equations to obtain unknowns x ₀ , y
Two sets of solutions A (x ₀₁ , y ₀₁ , z ₀₁ ), ₀ , z ₀ , B
(X ₀₂ , y ₀₂ , z ₀₂ ) is calculated. By applying appropriate coordinate conversion to A and B to obtain two points expressed in the longitude and latitude coordinate systems, and obtaining the formula of the straight line connecting these two points, a highly accurate linear approximate existence line with corrected time error (Formula of straight line in longitude and latitude coordinate system) is obtained. When the longitude coordinate is defined as w and the latitude coordinate is defined as z, the straight line formula is generally expressed as aw + bz = c (where a, b, and c are arbitrary constants) (6), and therefore the existence line LN is It will be determined by the values of a, b, and c.

Returning to FIG. 1, reference numeral 10 is a navigation controller having a microcomputer, which causes the CRT display device 3 to display a map image including the vehicle position together with the vehicle position mark by using the map data stored in the CD-ROM 1. Of these, 11 is a buffer memory for temporarily storing the map data read from the CD-ROM 1, 12 is a map image drawing unit, and a background layer and characters are included in the map data stored in the CD-ROM 1 during traveling.・ A map image including a park, rivers, roads, place names, map symbols, etc. in which a central map including the current location and eight peripheral maps are integrated into a video RAM described later using data such as symbol layers ( Draw 9 screens).

Reference numeral 13 denotes a map matching unit, which is a GPS
When the receiver 5 performs three-dimensional positioning or two-dimensional positioning, the vehicle position data input from the GPS receiver 5 is projected by using the map data stored in the CD-ROM 1 or the pattern matching method or the like. Map matching is performed according to the above, and the map is corrected and output to the map image drawing unit 12. When the GPS receiver 5 performs one-dimensional positioning, the presence line data (specifically, a, b, and
While inputting c), using the road data in the map data (see FIG. 9), the road on which the vehicle position obtained most recently in the past is, or the road connected to the road,
A new vehicle position (longitude, latitude) is calculated by calculating the intersection with the existing line near the vehicle position, and the vehicle position data is output to the map image drawing unit 12.

FIG. 3 is an explanatory diagram of a vehicle position detecting method by the map matching unit 13 when the one-dimensional positioning is performed. As shown in FIG. 3, the road RD _a the vehicle extending NE while traveling in the northeast, GPS receiver 5 performs three-dimensional positioning to _zero point Q, to t ₁ seconds after the positioning of the Q ₀ points as a result of one-dimensional positioning is performed the next positioning, when present line of linear approximation becomes LN _1, the vehicle direction theta ₀ (vehicle direction theta at Q ₀ point a measure clockwise true north as 0 ° to) the vehicle speed v _0, such as enclosed by the required time t ₁ Tokyo from Q ₀ by dashed lines, around the Q _0, radius v ₀ t ₁ +
A fan-shaped existence area M ₁ oriented with the vehicle direction θ ₀ is defined by the size of α. θ ₀ and v ₀ are obtained at the time of three-dimensional positioning with Q ₀ . Then, in the existing area M ₁ , the road R
Position of an intersection to Q ₁ exists line LN ₁ and D _a a (longitude, latitude) was calculated, with the new vehicle position data, contrary to the Q ₀ as viewed from the direction (to Q ₁ road RD _a in Q ₁ The direction of the direction (here, northeast) is the vehicle direction θ ₁ at Q ₁ .

Further, Q₁From point positioning t₂Made in seconds
As a result of one-dimensional positioning in the next positioning, a linear approximation existence line
LN₂Q becomes₁Vehicle direction at point θ₁And Q₀point
Vehicle speed v₀, Q₁Time t from₂And the dashed line from
Q surrounded by₁Fan-shaped existence area M centered on₂
The existence area M₂Inside the road RD_aAnd existence line LN
₂Intersection Q of₂Calculate the position (longitude, latitude) of the new car
Both position data and Q₂Direction of the road in
(Q₂Seen from Q₁Q direction) ₂Car in
Both positions θ₂And

Hereinafter, as long as one-dimensional positioning continues, the same processing is performed.
Repeatedly, the vehicle position and the vehicle direction Q ₃, Θ₃, Q_Four, Θ
_Four, ... If you are on the way, Q_n-1Next to
The one-dimensional positioning performed_n-1Existence centered on
Rear M_nIn the road RD_aBesides, the road RD_aConnected with
Road RD_bPresence area M_nin
Present line LN_nIs road RD_aAnd RD_bIntersect with both
However, in this case, the road R
D_aIntersection Q above_nThe new vehicle position by prioritizing the position of
And Q_nRoad RD_aDirection of Q_nVehicle orientation at
θ_nHowever, the road RD_bIntersection Q above_nPosition of'and Q
_nRoad RD in '_bDirection θ_n´ is preliminary data
And remember it.

Then, regarding the next one-dimensional positioning, FIG.
As shown in (1), Q_nArea M centered on_{n + 1}
In the presence line LN_{n + 1}Is road RD_aOr RD_bNoi
If you intersect with the gap, Q_nAnd θ_nNew vehicle position using
Q_{n + 1}And θ_{n + 1}And conversely, as shown in FIG.
Q_nArea M centered on_{n + 1}In the presence line LN
_{n + 1}Is road RD_aOr RD_bNot intersect with any of
When I got a Q_nAnd θ _nAs preliminary data for
It was Q_n´ and θ_n´ is the previous official vehicle position and vehicle direction
Replace with new vehicle position Q_{n + 1}And θ_{n + 1}Ask for
To do so. This caused the vehicle to turn left at the intersection CP.
You will understand. The map matching unit 13 is shown in FIG.
As shown in, the latest vehicle position data, vehicle orientation data,
A first memory area for storing vehicle speed data and a spare position data
Has a second storage area for storing multiple sets of data and direction data
Built-in memory.

Returning to FIG. 1, reference numeral 14 denotes a video RAM having a storage area of a size corresponding to nine screens, for storing the map image drawn by the map image drawing unit 12, and 15 for the map drawing control unit 12. Video RA under read control
A read control unit that reads out an image for one screen centered on the vehicle position, which is drawn in M14, 16 is a vehicle position mark generation unit that generates a predetermined vehicle position mark in the vehicle azimuth direction, and 17 is read control A synthesizing unit for synthesizing the vehicle position mark at the center of the image read by the unit 15, and 18 for converting the image synthesized by the synthesizing unit 17 into a predetermined video signal to C
This is a video conversion unit for outputting to the RT display device 3.

FIG. 6 is a flow chart showing the operation of the processing unit 8 of the GPS receiver 5, and FIGS. 7 and 8 are flow charts showing the operation of the navigation controller 10, which will be described below with reference to these figures. The navigation message demodulated by the demodulation unit 7 is stored in the buffer memory 8a by interrupt processing, but the flow chart of the interrupt processing is omitted. Also,
In the buffer memory 8a, it is assumed that the navigation message received in the past and each data of longitude, latitude, and altitude detected in the past are stored in advance. Furthermore, the vehicle runs northeast from the ST point along the road RD _a in FIG.
After that, turn left at the intersection CP and proceed northwest along the road RD _b .

When the power of the set is turned on, the positioning unit 8b of the GPS receiver 5 first uses the navigation message stored in the buffer memory 8a to determine the satellite currently existing above the vehicle, and the demodulation unit. 7 is controlled to simultaneously track a large number of satellites (step 101 in FIG. 6). And 5
When two or more satellite radio waves can be captured (step 102)
YES), the satellite position is calculated, and the DOP value (PDOP value) becomes the smallest among the captured satellites. 4
Pseudo range signals are input from the demodulation unit 7 to one satellite group and the vehicle position (longitude, latitude, altitude) is measured by three-dimensional positioning by satellite navigation (step 103). However, when only four satellite radio waves can be captured by the demodulation unit 7 when driving in urban areas or in mountainous areas, targeting the four satellite groups,
The vehicle position (longitude, latitude, altitude) is measured by three-dimensional positioning by satellite navigation by inputting a pseudo range signal from the demodulation unit 7.

When only three satellite radio waves can be captured, a pseudo range signal is input from the demodulation unit 7 to the three satellite groups and the vehicle position (longitude, longitude, etc.) is determined by two-dimensional positioning by satellite navigation. The latitude is measured (steps 104 and 10)
5). In this two-dimensional positioning, the latest altitude data stored in the buffer memory 8a is used. Immediately after the power is turned on, even if only two satellite radio waves can be captured,
The dimensional positioning is not performed, and the positioning unit 8b causes the demodulation unit 7 to continue tracking the satellites until three or more satellite radio waves can be captured (NO in step 109).

In this way, when the positioning unit 8b positions the vehicle by three-dimensional positioning or two-dimensional positioning, the azimuth vector calculation unit 8c inputs the Doppler amount signal from the demodulation unit 7 to calculate the azimuth vector. (Step 10
6). When calculating the azimuth vector, the satellite position data and the vehicle position data obtained when the positioning unit 8b performs positioning by satellite navigation are used. Then, the positioning unit 8b and the azimuth vector calculation unit 8c indicate the vehicle position data (the longitude and the latitude of the ST point in FIG. 3) initially measured after the power is turned on and the calculated vehicle azimuth data (the direction of the azimuth vector is shown). data)
And vehicle speed data (data indicating the magnitude of the azimuth vector) are output to the navigation controller 10 together with data indicating the positioning dimension (three-dimensional or two-dimensional),
Enable predetermined navigation processing (step 10
7) Also, the vehicle position data measured this time is updated and stored in the buffer memory 8a (step 108).

However, when the positioning unit 8b can perform three-dimensional positioning when updating and storing in step 108, all of the longitude, latitude, and altitude are updated and stored, but when only two-dimensional positioning is possible, longitude and latitude are stored. Only update and store. After that, the processing unit 8 returns to step 101, and thereafter, when there are three or more satellite signals that can be similarly received from the vehicle,
Three-dimensional positioning or two-dimensional positioning by satellite navigation and calculation of the vehicle direction vector (vehicle direction and vehicle speed) are repeated.

On the other hand, the navigation controller 10
After the power is turned on, the map matching unit 13 waits for the first positioning (three-dimensional positioning or two-dimensional positioning) in the GPS receiver 5 to be completed (step 201 in FIG. 7), and if the first positioning is completed, For example, the vehicle position data (longitude and latitude of the ST point in FIG. 3), the vehicle direction data and the vehicle speed data are input from the GPS receiver 5, of which the vehicle direction data and the vehicle speed data are stored in the internal memory as regular data. The data is stored in the first storage area (step 202, see FIG. 5) and the vehicle direction data is output to the vehicle position mark generation unit 16.
Next, map data in a predetermined range around the vehicle position is read from the CD-ROM 1 and stored in the buffer memory 11 (step 203), and map matching is performed using the road data (see FIG. 9) in the read map data. The vehicle position is corrected on the road RD _a (step 204), and the corrected vehicle position data is stored in the first storage area of the built-in memory as regular data and the map image drawing unit 12
(Step 206). Then, the timer T is started (step 207).

Next, the map image drawing section 12 is based on the vehicle position data input from the map matching section 13 and selects one of the center one of the map images drawn in the video RAM 14.
It is checked whether the vehicle position is included in the one map (step 206). Since it is NO at the beginning, the map data stored in the buffer memory 11 is used for the video RAM.
A map image in which one central map including the vehicle position and eight maps surrounding the map are integrated into 14 is drawn (step 208).

Subsequently, the map image drawing section 12 gives read center position data corresponding to the vehicle position on the video RAM 14 to the read control section 15 to perform read control, and the read control section 15 causes the video RAM 14 to operate. A map image of the size of one screen centered on the vehicle position is read from (step 209). Next, the vehicle position mark generation unit 17 generates a predetermined vehicle position mark oriented in the vehicle azimuth direction based on the vehicle azimuth data input from the map matching unit 13 (step 210). The vehicle position mark is combined by the combining unit 18 at the center of the image for one screen read from the video RAM 14, and then converted into a predetermined image signal by the image conversion unit 19. Then, it is output to the CRT display device 3 and displayed on the screen (step 211). As a result, it is possible to easily confirm at which point the vehicle is currently located, and it is also possible to check an appropriate traveling route to a desired place.

After this, the navigation controller 1
0 indicates that the map matching unit 13 waits until the GPS receiver 5 completes the next positioning (step 212), and if so, checks whether three-dimensional positioning or two-dimensional positioning has been performed, or whether one-dimensional positioning has been performed. Yes (Step 2
13). When three-dimensional positioning or two-dimensional positioning is performed, new vehicle position data (longitude,
Latitude), vehicle direction data and vehicle speed data,
Among these, the vehicle azimuth data and the vehicle speed data are updated and stored as regular data in the first storage area of the built-in memory (step 202), and the vehicle azimuth data is output to the vehicle position mark generation unit 16. Then CD-ROM
Necessary map data around the vehicle position is read from 1 and stored in the buffer memory 11 (step 203), and map matching is performed using the road data in the map data to correct the vehicle position on the road RD _a (step 204). The corrected vehicle position data is stored in the first storage area of the built-in memory as regular data and is output to the map image drawing unit 12 (step 205). Then, the timer T is restarted (step 206).

The map image drawing unit 12, which has received the new vehicle position data, checks whether the vehicle position is included in one map at the center among the map images drawn in the video RAM 14 ( Step 207). If NO, the map data is used to redraw a map image in which one central map including the vehicle position and eight maps surrounding the map are redrawn in the video RAM 14 (step 20).
8) and proceeds to step 209. If YES in step 207, the process directly proceeds to step 209 without redrawing the map image.

In step 209, the map image drawing unit 12
Supplies read center position data corresponding to the vehicle position on the video RAM 14 to the read control unit 15 to perform read control.
A map image having the size of one screen centered on the vehicle position is read from the AM 14. Next, the vehicle position mark generation unit 17 generates a predetermined vehicle position mark oriented in the vehicle azimuth direction based on the vehicle azimuth data input from the map matching unit 13 (step 210). The vehicle position mark is combined by the combining unit 18 at the center of the image for one screen read from the video RAM 14, and then converted into a predetermined image signal by the image conversion unit 19. And C
It is output to the RT display device 3 and displayed on the screen (step 211). As a result, if the vehicle is moving, the map image on the screen is scrolled while keeping the vehicle position at the center. Hereinafter, three-dimensional positioning or 2 with the GPS receiver 5
The navigation controller 10 repeats the same processing while the dimensional positioning is continued.

After that, after three-dimensional positioning or two-dimensional positioning is continuously performed up to the point Q ₀ in FIG. 3, the vehicle enters the building street, and the demodulator 7 of the GPS receiver 5 has only two satellites. When it cannot be captured, the processing unit 8b determines YES in step 110 of FIG. 6, and targets the two satellite groups,
A pseudo-range signal is input from the demodulation unit 7 and the existence line of the vehicle position is calculated by one-dimensional positioning by satellite navigation (step 111). In this one-dimensional positioning, the buffer memory 8a
Utilizing the latest vehicle position data (longitude, latitude, altitude) stored in, the above equations (3) to (5) are combined in 4
Solves two simultaneous equations, 2 in the X, Y, Z Cartesian coordinate system
The solution of the set is obtained, further converted to the longitude and latitude coordinate systems, the equation of the straight line connecting the two points in the longitude and latitude coordinate systems is obtained, and the straight line approximated existence line is obtained. If the longitude coordinate is w and the latitude coordinate is z, the existence line is generally aw + bz =
Since it can be expressed as c (however, a, b, and c are arbitrary constants),
The existence line is determined by the values of a, b, and c.

After determining the existence line by one-dimensional positioning, the positioning unit 8b outputs the existence line data (values of a, b, and c) to the navigation controller 10 together with the data indicating the present positioning dimension (one-dimensional). (Step 112). Then, the vehicle waits for input of vehicle position data (here, longitude and latitude) from the navigation controller 10 for a fixed time, and if there is an input, it is updated and stored in the buffer memory 8a (step 113). Then, the process returns to step 101, and next. Positioning is performed. If the vehicle position data is not input within the fixed time in step 113, the process directly returns to step 101.

On the other hand, the navigation controller 10
The map matching unit 13 uses the GPS receiver 5 for one-dimensional measurement.
If it is ranked, it is judged as NO in Step 213 of FIG.
Line data is input (step 301 in FIG. 8). Continued
Around the vehicle position stored in the buffer memory 11
Road data (see Figure 9) in the first storage area of the internal memory
Vehicle position Q, which is the latest stored regular data₀, Q
₀Vehicle orientation at₀And vehicle speed v₀(First memory of FIG. 5
(Data stored in the area), the time t of the timer T ₁For
And the existence area M as shown in FIG.₁Determine (step
302). And the existing area M₁In the vehicle
Position RD_aAnd the road RD_aConnected with
Roads and existing lines LN₁Position of intersection with (longitude, latitude
Degree), the road direction at the intersection is calculated (step 3)
03). However, whether the road direction at the intersection is road data
Can be obtained from the intersection, but from the intersection Q₀The direction you saw
Q₀Since there are two types in the opposite direction to,₀What is
The direction is the opposite direction.

Next, the map matching unit 13 checks whether or not there is one or more intersection points obtained in step 303 (step 304), and if YES, checks whether there are multiple points (step 305). Since intersection in existing area M ₁ is only one of Q _1, together YES is determined in step 304 and 305, in this case, a new intersection to Q ₁ longitude, and latitude, the road direction theta ₁ in Q ₁ After updating and storing in the first storage area of the built-in memory as the regular vehicle position data and vehicle azimuth data (step 306), the vehicle azimuth data θ ₁ and the vehicle position data Q ₁ are drawn on the map image. Output to the unit 12. The vehicle position data Q ₁ is also output to the GPS receiver 5 (step 30).
7). Then, the process proceeds to step 206 of FIG. 7 and the timer T
To restart. Navigation controller 10
The positioning unit 8b which has input the vehicle position data (longitude and latitude here) is updated and stored in the buffer memory 8a (see FIG. 6).
Step 113).

The map image drawing unit 12, which has received the new vehicle position data, checks whether the vehicle position is included in the central one of the map images drawn in the video RAM 14 ( Step 207). If NO, the map data is used to redraw a map image in which one central map including the vehicle position and eight maps surrounding the map are redrawn in the video RAM 14 (step 20).
8) and proceeds to step 209. If YES in step 207, the process directly proceeds to step 209 without redrawing the map image.

In step 209, the map image drawing unit 12
Supplies read center position data corresponding to the vehicle position on the video RAM 14 to the read control unit 15 to perform read control.
A map image having the size of one screen centered on the vehicle position is read from the AM 14. Next, the vehicle position mark generation unit 17 generates a predetermined vehicle position mark oriented in the vehicle azimuth direction based on the vehicle azimuth data input from the map matching unit 13 (step 210). The vehicle position mark is combined by the combining unit 18 at the center of the image for one screen read from the video RAM 14, and then converted into a predetermined image signal by the image conversion unit 19. And C
It is output to the RT display device 3 and displayed on the screen (step 211). As a result, even if there are two satellites that can be captured from the vehicle, the accurate vehicle position can be displayed on the screen.

The next positioning performed by the GPS receiver 5 is also one-dimensional positioning. As shown in FIG. 3, the linear approximate existence line is LN ₂
And when it becomes, the map matching unit 13, a vehicle speed v _0, Q ₁ such as enclosed by a broken line from the required time t ₂ Metropolitan from Q ₁ in the vehicle azimuth theta ₁ and Q ₀ points at ₁ point Q A fan-shaped existence area M ₂ at the center is determined, the position (longitude, latitude) of the intersection Q ₂ of the road RD _a and the existence line LN ₂ is calculated in the existence area M ₂ , and Q ₁ to Q ₂ are viewed. Road RD close to the direction
calculating the direction theta ₂ of _a (step 213 of FIG. 7, FIG. 8
Steps 301 to 303).

Next, the map matching unit 13 checks whether or not there is one or more intersection points obtained in step 303 (step 304), and if YES, checks whether there are multiple points (step 305). Since intersection in existing area M ₂ is only one of Q _2, together YES is determined in step 304 and 305, in this case, a new intersection Q ₂ longitude, and latitude, the road direction theta ₂ in Q ₂ After updating and storing the regular vehicle position data and the vehicle direction data in the first storage area of the built-in memory (step 306), the vehicle direction data θ ₂ is drawn in the vehicle position mark generator 16, and the vehicle position data Q ₂ is drawn in a map image. Output to the unit 12. The vehicle position data Q ₂ is also output to the GPS receiver 5 (step 30)
7). Then, the process proceeds to step 206 of FIG. 7 and the timer T
To restart. Navigation controller 10
The positioning unit 8b which has input the vehicle position data (longitude and latitude here) is updated and stored in the buffer memory 8a (see FIG. 6).
Step 113).

Hereinafter, as long as one-dimensional positioning continues, the same processing is performed.
Repeatedly, the vehicle position and the vehicle direction Q ₃, Θ₃, Q_Four, Θ
_Four, ... Enter new vehicle position data
The map image drawing unit 12
Of the map images drawn in, the car in the center one map
Check if both positions are included (step 20)
7). If NO, video RA using map data
In M14, one map in the center including the vehicle position and the location
Redraw the map image that integrates the eight maps surrounding the figure
Then (step 208), the process proceeds to step 209. In addition,
If YES in step 207, the map image is not redrawn.
Without doing so, the process directly proceeds to step 209.

Then, the map image drawing unit 12 gives read center position data corresponding to the vehicle position on the video RAM 14 to the read control unit 15 for read control, and causes the read control unit 15 to read from the video RAM 14. A map image having the size of one screen centered on the vehicle position is read out. In addition, the vehicle position mark generation unit 17, based on the vehicle direction data input from the map matching unit 13,
A predetermined vehicle position mark oriented in the vehicle azimuth direction is generated (step 210). The vehicle position mark is combined by the combining unit 18 at the center of the image for one screen read from the video RAM 14, and then converted into a predetermined image signal by the image conversion unit 19. Then, it is output to the CRT display device 3 and displayed on the screen (step 21).
1). As a result, even if the GPS receiver 5 cannot perform three-dimensional positioning or two-dimensional positioning, if one-dimensional positioning is possible,
The vehicle position mark on the screen is moved and displayed at the correct position on the map without being fixed at Q ₀ .

[0055] Then, because the vehicle is approaching an intersection CP road RD _a and RD _b, as shown in FIG. 3, for one-dimensional positioning it has been made in the following Q _n-1, the presence area around the Q _n-1 in addition to the road RD _a in M _n, when also contains road RD _b which led the road RD _a, there line LN _n in presence area M _n intersects with both the road RD _a and RD _b. At this time, the map matching unit 13 determines NO in step 305 of FIG.

In this case, the map matching unit 13
Road RD that has been running until now_aIntersection Q above_nAnd Q_nIn
Road RD_aNew normal vehicle position and priority
And vehicle direction θ_nIs updated in the first storage area of the internal memory as
Remember, the road RD _bIntersection Q above_nPosition of
And Q_nRoad RD at '_bDirection θ_n´ is Q_n, Θ_nTo
It is recorded in the second storage area of the internal memory as spare data for
Remember (step 308). Vehicle heading data θ_nIs
Vehicle position mark generator 16, vehicle position data Q_nIs a map
The image data is output to the image drawing unit 12, and the vehicle position data Q_nIs GPS
It is also output to the receiver 5 (step 307). And the figure
7. Go to step 206 of 7 and restart timer T
It As a result, the vehicle position mark on the screen is Q_nMove to position
Move.

However, if the vehicle turns left at the intersection CP, G
Regarding the next one-dimensional positioning made by the PS receiver 5,
As shown in FIG. 4 (2), Q_nArea M centered on
_{n + 1}In the presence line LN_{n + 1}Is road RD_aOr RD_b
The map matching unit 13
Is determined to be NO in step 304. This place
Q in the built-in memory_n, Θ_nPreliminary data for
Check if it is remembered (step 309 in FIG. 8),
Q here_n´, θ_n´ exists, so these are the last time
As the regular vehicle position and vehicle azimuth (step 31
0), Q_nPresence area M centered on_{n + 1}among,
Existence line LN_{n + 1}Is road RD_bQ that intersected with _{n + 1}And Q
_{n + 1}Road RD_bDirection θ_{n + 1}Ask (step
302, 303). At this time, there is only one intersection
Q_{n + 1}And θ_{n + 1}The regular vehicle position data and vehicle
When the data is updated and stored in the first storage area of the built-in memory as a data
In each case, the map image drawing unit 12 and the vehicle position mark generation unit
It outputs to 16 (304-306). This allows the screen
Vehicle position mark is road RD_bIs displayed above
You can see that the vehicle turned left at the intersection CP.

If the vehicle goes straight through the intersection CP, as shown in FIG. 4 (1), the existence line LN _{n + 1 corresponds} to the road RD _a in the existence area M _{n + 1} centered on Q _n. And Q _{n + 1}
Since it intersects at a point, YES is obtained in step 304, and the road R
The intersection point Q _{n + 1} with D _a and the direction θ of the road RD _a at the intersection point
_{n + 1} may be used as it is as a new vehicle position and vehicle direction.

After that, while traveling northwest along the road RD _b , the GPS receiver 5 is restarted from the point Q _{i in} FIG. 4 (2).
When the three-dimensional positioning or the two-dimensional positioning becomes possible, the navigation controller 10 determines YES in step 213 of FIG. 7, and then proceeds to step 202 to map the vehicle position data measured by the GPS receiver 5. Correct on road RD _b by matching. Then, based on the corrected vehicle position, the vehicle position mark is displayed at the corresponding position on the map image.

According to this embodiment, when the number of satellites that can be captured from the vehicle becomes two, the GPS receiver 5 performs one-dimensional positioning to obtain the existing line where the vehicle is located, and the map matching unit 13 In order to detect a new vehicle position, the road data is used to find the intersection of the road on which the vehicle has been traveling or the road connected to the road and the existing line in the vicinity of the vehicle position. Even if three-dimensional positioning or two-dimensional positioning cannot be performed, the vehicle position can be continuously detected, and the driver can be provided with the correct vehicle position.

In the above embodiment, the size of the existing area is determined by multiplying the vehicle speed at the time of the last three-dimensional positioning or two-dimensional positioning by the time interval of the one-dimensional positioning and adding a constant. However, it may simply be a size obtained by multiplying the vehicle speed by the time interval of the one-dimensional positioning, or may be a fixed size, or the vehicle speed extracted from the speedometer equipped in the vehicle during the one-dimensional positioning. May be determined by multiplying by the time interval of one-dimensional positioning and adding a constant. After the one-dimensional positioning, the road data is used to find the intersection of the road on which the vehicle has traveled or the road connected to the road and the existing line in the vicinity of the vehicle position to obtain a new vehicle position. The process of detecting
It may be performed by the processing unit of the receiver. Further, the vehicle position mark may be blinked during the one-dimensional positioning so that the driver can recognize that the one-dimensional positioning is currently being performed.

As the altitude data used for two-dimensional positioning and one-dimensional positioning, predetermined fixed data may be used, or the altitude data may be stored in the map data in association with each node. Alternatively, the altitude data may be read and used.

[0063]

As described above, according to the present invention, when neither three-dimensional positioning nor two-dimensional positioning is possible during positioning of a vehicle position by satellite navigation, one-dimensional positioning is performed using known altitude data. , Find the line of existence of the vehicle on a spherical surface where the altitude is constant with the known value when viewed from the center of the earth, refer to the road data, and connect to the road on which the vehicle position obtained last time or the road Since it is configured to calculate a new vehicle position by calculating the intersection of the existing road and the existing line in the vicinity of the vehicle position, only two satellites that can receive satellite radio waves from the vehicle while traveling in a building street, etc. Even if it doesn't exist,
The vehicle position can be detected, and the vehicle position detection rate by satellite navigation can be greatly improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a vehicle-mounted navigation device that embodies a vehicle position detection method according to the present invention.

FIG. 2 is a diagram illustrating the principle of one-dimensional positioning by a GPS receiver.

FIG. 3 is an explanatory diagram of a vehicle position detection method by a map matching unit at the time of one-dimensional positioning.

FIG. 4 is an explanatory diagram of a vehicle position detection method by a map matching unit at the time of one-dimensional positioning.

FIG. 5 is an explanatory diagram of data stored in a built-in memory of a map matching unit.

FIG. 6 is a flowchart showing the operation of the GPS receiver.

FIG. 7 shows a first operation of the navigation controller.
2 is a flowchart of.

FIG. 8 is a second diagram showing the operation of the navigation controller.
2 is a flowchart of.

FIG. 9 is an explanatory diagram of data stored in a road layer.

FIG. 10 is an explanatory diagram of three-dimensional positioning and two-dimensional positioning.

[Explanation of symbols]

 1 CD-ROM 3 CRT display device 5 GPS receiver 7 demodulation unit 8 processing unit 10 navigation controller 12 map image drawing unit 13 map matching unit 14 video RAM 16 vehicle position mark generation unit

Claims (1)

[Claims] 1. During positioning of a vehicle position by satellite navigation, 3
When both two-dimensional positioning and two-dimensional positioning become impossible, one-dimensional positioning is performed using known altitude data, and the presence line of the vehicle on a spherical surface where the altitude is constant at the known value when viewed from the center of the earth. Then, by referring to the road data, a new vehicle position is calculated by calculating the intersection of the road on which the vehicle position previously obtained or the road connected to the road and the existing line near the vehicle position are calculated. The vehicle position detecting method characterized by the above.