JPH06331368A - Vehicle position correction system - Google Patents

Abstract

PURPOSE:To correct the position of a vehicle and a running bearing using a position data and a bearing data with a GP3 when map matching becomes impossible by a self-contained navigation. CONSTITUTION:When map matching becomes impossible, a map matching processing section 6e-2 uses a GPS data to judge that a difference is below a threshold between a vehicle speed computed using a GPS data and that to be obtained with a self-contained navigation sensor 5 is below a threshold and wher the speed difference is below the threshold, the current position of the vehicle and the running bearing are corrected using the GPS position data and bearing data.

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 a navigation system in which a three-dimensional positioning function by GPS (Grobal Positioning System) is added to self-contained navigation using a distance sensor and a direction sensor. Regarding method.

[0002]

2. Description of the Related Art A navigation system reads map data corresponding to the current position of a vehicle from a map data storage unit such as a CD-ROM and draws it on a display screen.
The vehicle position mark is moved on the map, or the vehicle position mark is fixedly displayed at a fixed position on the display screen (for example, the center position of the display screen), and the map is scrolled according to the movement of the vehicle. The map data is (1)
It is composed of a road layer consisting of road data, road link data, intersection data, etc., (2) a background layer for displaying objects on the map, and (3) a character layer for displaying city names, etc. The map image displayed on the screen is generated based on the background layer and the character layer, and the map matching process and the guidance route search process are performed based on the road layer. In such a navigation system, it is essential to measure the current position of the vehicle. Therefore, conventionally, a measurement method for measuring the vehicle position by using a distance sensor and a direction sensor mounted on the vehicle (self-contained navigation) and a measurement method by GPS using a satellite (satellite navigation) have been put into practical use. The vehicle position measurement by self-contained navigation can measure the vehicle position at a relatively low cost, but there is a problem that the position measurement cannot be performed with high accuracy, and correction processing such as map matching processing is required. In addition, while satellite navigation can detect an absolute position, it has a drawback that the position cannot be detected in a place where satellite radio waves are blocked, such as a tunnel or a building.

In a self-contained navigation device,
The vehicle position is detected as follows by integration based on the outputs of the distance sensor and the relative azimuth sensor. FIG. 5 is an explanatory diagram of a vehicle position detection method by self-contained navigation. The distance sensor outputs a pulse each time the vehicle travels a certain unit distance L ₀ , and the reference azimuth (θ = 0) is set on the X axis. Forward direction,
The counterclockwise direction from the reference azimuth is defined as the + direction. The previous vehicle position is point P ₀ (X ₀ , Y ₀ ), the absolute heading of the vehicle at the point P ₀ is θ ₀ , and the output of the relative heading sensor at the time of traveling the unit distance L ₀ is Δθ ₁ . Then, the change amount of the vehicle position is ΔX = L ₀ · cos (θ ₀ + Δθ ₁ ) ΔY = L ₀ · sin (θ ₀ + Δθ ₁ ), and the absolute direction θ of the vehicle traveling direction at this point P ₁ is θ. ₁ and the position (X ₁ , Y ₁ ) are θ ₁ = θ ₀ + Δθ ₁ (1) X ₁ = X ₀ + ΔX = X ₀ + L ₀ · cos θ ₁ (2) Y ₁ = Y ₀ + ΔY = Y ₀ + L ₀・ It can be calculated by vector composition as sin θ ₁ (3). Therefore, if the absolute azimuth and position coordinates of the vehicle at the start point are given, then each time the vehicle travels a unit distance, the vehicle position can be detected in real time by repeating the calculations of equations (1) to (3). The vehicle position mark and the running track can be displayed on the road.

However, in self-contained navigation, there are
The difference is cumulative and the vehicle position deviates from the road. Therefore,
The vehicle position is compared with the road data by
And fix it on the road. Various map matching methods are available.
Is being proposed. The first map matching method is
Save the trace (position and direction for each predetermined mileage),
Find a road on the map that has the same shape as the running path, and
By using the method of map matching the vehicle position mark to the
is there. The second map matching method is the projection method
Is. 6 to 7 show map matching by the projection method.
FIG. Vehicle position is point P_i-1(X_i-1, Y_i-1) To
Yes, vehicle direction is θ_i-1(Point P in FIG. 6)
_i-1Indicates the case where the road does not coincide with RDa). Point P
_i-1More constant distance L₀Relative when traveling (for example, 5 m)
Azimuth is Δθ_iIf so, the point of the vehicle position by self-contained navigation
P_i′ (X_i′, Y_i′) And P_iVehicle direction at ′_iIs next
Formula θ_i= Θ_i-1+ Δθ_i  X_i′ = X_i-1+ L₀・ Cos θ_i  Y_i′ = Y_i-1+ L₀・ Sin θ_i Required by.

[0005] At this time, 'a link possible from the taking down perpendicular, point P _i' (a) point P _i heading theta _i in
And the angle formed by the link is within a certain value, and the length of the perpendicular line drawn from the point P _i ′ to the link is within a certain distance. Here, the link LKa ₁ (the straight line connecting the nodes Na ₀ and Na ₁ ) of the direction θa ₁ on the road RDa and the road RD
This is a link LKb ₁ (a straight line connecting the nodes Nb ₀ and Nb ₁ ) with the direction θb ₁ on b. Then, (b) link LKa from point P _i ′
_The lengths of the vertical lines RLia and RLib dropped to ₁ and LKb ₁ are obtained, and the shorter link is used as a matching candidate. Here, the link is LKa ₁ . (c) The traveling locus SHi connecting the points P _i-1 and P _i ′ is translated in the direction of the perpendicular line RLia until the point P _{i -1} is on the link LKa ₁ (or on the extension line of the link LKa ₁ ). The moving points PT _i-1 and P _{i of} the points P _i-1 and P _i ′.
T _i ′ is obtained, and (d) Finally, PT _i ′ is centered on the point PT _i−1.
Is moved on the link LKa ₁ (or on the extension of the link LKa ₁ ) to obtain the moving point, and the corrected vehicle position P _i
(X _i , Y _i ). The vehicle direction at the corrected vehicle position P _i remains θ _i . Further, as shown in FIG. 7, when the point P _i-1 which is the previous vehicle position is on the road RDa, the moving point PT _i-1 coincides with the point P _i-1 .

[0006]

By the way, in the self-contained navigation, when the error becomes large and the vehicle position deviates greatly from the road, the vehicle position cannot be map-matched to the actual current position on the road. That is, the first map matching method cannot find a road having the same shape as the traveling locus,
Also, the second method makes it impossible to find a road that satisfies the matching condition. When the map matching becomes impossible in this way, the navigation does not make sense, and the vehicle must be stopped and the vehicle position mark must be positioned at the actual vehicle position on the map to restart the navigation. However, such a method has extremely poor operation performance. Therefore, if GPS is incorporated into a self-contained navigation system and map matching becomes impossible, the position of the vehicle and the direction data obtained from the GPS are used to map match the vehicle position with the current position of the vehicle, and the traveling direction of the vehicle. It is possible to correct.

However, as described above, although the absolute position can be detected by GPS, accurate position detection cannot be performed in a place where satellite radio waves are blocked, such as a tunnel or a building, and the receiving satellite is switched. And SA (Selectable Avail
to the position detected by GPS when switching
In this way, if map matching by self-contained navigation becomes impossible at the time when the position and direction measured by GPS include many errors, the GPS including errors will be generated.
The vehicle position and the traveling direction will be corrected using the position data and direction data according to, and the vehicle position mark cannot be correctly map-matched to the actual vehicle position on the map.
Moreover, the traveling direction also differs from the actual traveling direction. In view of the above, an object of the present invention is to provide a vehicle position correction method capable of correcting a vehicle position and a traveling direction using correct GPS position data and direction data when map matching by self-contained navigation becomes impossible. is there.

[0008]

According to the present invention, the above-mentioned problems are solved by a vehicle position / azimuth calculation unit for calculating a vehicle position and a traveling azimuth by self-contained navigation, a vehicle speed calculated using position data obtained from a GPS and an autonomous stance. A speed difference monitoring unit that determines the difference from the vehicle speed obtained from the navigation sensor and determines whether the difference is less than or equal to a threshold value. When map matching becomes impossible, when the speed difference is less than or equal to the threshold value. This is achieved by a map matching processing unit that corrects the vehicle position and traveling direction using GPS position data and direction data.

[0009]

Operation: When map matching becomes impossible, GPS
The difference between the vehicle speed calculated using the obtained position data and the vehicle speed obtained from the distance sensor is determined, and it is determined whether the difference is less than or equal to a threshold value. When the speed difference is less than or equal to the threshold value, the GPS
The vehicle position and traveling direction are corrected using the position data and direction data. In this way, the vehicle position and azimuth are corrected using the GPS data only when the speed difference is less than or equal to the threshold value. Therefore, the GPS data can be trusted and the correct position and azimuth can be corrected.

[0010]

【Example】

Overall Configuration FIG. 1 is a configuration diagram of a navigation system which is an embodiment of the present invention, and 1 is a CD-RO for storing map information.
M is a control panel, 3 is a GPS receiver that receives radio waves from satellites to measure the current position of the vehicle, 4 is a multi-beam antenna that receives radio waves from each satellite, and 5 is a self-contained navigation sensor. Reference numeral 5a is a relative azimuth sensor (angle sensor) that detects the rotation angle of the vehicle such as a vibration gyro, 5b is a distance sensor that generates one pulse for each predetermined traveling distance, 6 is a map and vehicle position mark drawing processing, and is optimal. A system controller having a microcomputer configuration for performing route search processing, map matching processing, and the like, and a display device 7.

Map information Map information is composed of (1) road layer, (2) background layer for displaying objects on the map, (3) character layer for displaying names of cities, towns and villages, etc. There is.
Among them, the road layer includes road link data RLDT, node data NDDT, and intersection data C as shown in FIG.
It has an RDT. The road link data RLDT gives the attribute information of the relevant road, and all the road links
It is composed of data such as the number of roads, the number of each node forming the road, the road number (road name), and the type of road (national road, highway, other). Also, intersection data CRDT
Is a set of nodes (referred to as an intersection composing node) closest to the intersection among the nodes on the link connecting the intersections on the map, and the node data NDDT constitutes a road. It is a list of all nodes, position information (longitude, latitude) for each node, an intersection identification flag for whether or not the node is an intersection, and if the node is an intersection, it indicates intersection data. If it is not an intersection, it is composed of a pointer or the like that points to the road link to which the node belongs.

[0012] Operation panel operation panel 2 is provided with a joystick for relatively moving the vehicle position mark relative to the map, the map search key, enlargement / reduction key, various keys such optimal route search key. As shown in FIG. 3, the GPS receiver 3 is a frequency conversion / amplifier 3 for converting the radio waves from the respective satellites received by the multi-beam antenna 4 into a predetermined intermediate frequency signal and amplifying it.
a, a receiver 3b that selects and detects a channel signal assigned to GPS from radio waves from each satellite, a decoder 3c that decodes the channel signal into digital data (time code data, etc.), and a processing unit 3d. I have it. Processing unit 3
d performs three-dimensional positioning or two-dimensional positioning processing based on the decoded data to calculate and output the vehicle position, azimuth, and vehicle speed. Note that the azimuth is the direction connecting the current vehicle position and the vehicle position one sampling time ΔT before, and the vehicle speed is 1
The distance between vehicle positions before the sampling time ΔT is divided by the sampling time.

System controller The system controller 6 includes a map data buffer memory 6a for temporarily storing map data, a map read control unit 6b, and some of the latest position data, heading data, and vehicle speed measured by the GPS receiver 3. A data storage unit 6c that stores data, a vehicle position / direction calculation unit 6 that calculates the vehicle position and traveling direction based on the output of the self-contained navigation sensor
d, a vehicle position correction unit 6e that corrects the vehicle position, a vehicle position mark generation unit 6f, a map drawing control unit 6g that displays a map around the vehicle position together with the vehicle position mark on the display device 7, and a speed difference monitoring unit 6h. ing. The map read control unit 6b receives the current vehicle position, reads the map data corresponding to the current vehicle position from the CD-ROM 1 and stores it in the map data buffer memory 6a. The vehicle position / azimuth calculation unit 6d calculates the vehicle current position and the traveling azimuth according to the equations (1) to (3) based on the outputs of the angle sensor 5a and the distance sensor 5b. The vehicle position correction unit 6e uses a traveling locus storage unit 6e-1 that stores the vehicle position and traveling direction at predetermined time intervals as a traveling locus, and road data and traveling locus data read out to the map data buffer memory 6a. It has a map matching processing unit 6e-2 that corrects the vehicle position by performing map matching processing as described above. The vehicle position mark generator 6f receives the vehicle position data and generates a vehicle position mark on the current vehicle position on the map. The map drawing control unit 6g reads the map data around the current vehicle position and the vehicle position mark data from the map buffer memory 6a and the vehicle position mark generation unit 6f and inputs them to the display device 7. The speed difference monitoring unit 6h determines that the difference between the vehicle speed Vgps calculated based on the position data obtained by GPS and the vehicle speed Vcs calculated based on the output of the distance sensor 5b is a threshold value (for example, 5K).
m / h) or less.

Display Device The display device 7 includes a CRT controller 8, a video RAM (V-RAM) 9, a read control unit 10, and a CRT.
11 and the like, and displays a desired map and vehicle position mark on the CRT screen (screen). Overall Operation FIG. 4 is a flowchart of the map matching process of the present invention. The vehicle position / azimuth calculation unit 6d uses the outputs of the angle sensor 5a and the distance sensor 5b to calculate the current position and traveling azimuth of the vehicle at predetermined time intervals, and inputs them to the vehicle position correction unit 6e. The traveling locus storage unit 6e-1 of the vehicle position correction unit 6e sequentially stores the vehicle position and the direction input from the vehicle position / direction calculation unit 6d (step 101). The map matching processing unit 6e-2 performs the map matching processing by the described method for each predetermined traveling distance of the vehicle. If the matching is possible (step 102), the current vehicle position and the traveling direction are corrected, and the corrected value is set to the vehicle. The data is input to the position / azimuth calculation unit 6d and the vehicle position mark generation unit 6f (step 103). The vehicle position mark generation unit 6f generates a vehicle position mark so as to be displayed on the corrected current vehicle position, and the map drawing control unit 6g reads the vehicle position mark data from the vehicle position mark generation unit 6f and displays it on the display device 7. To display the corrected position on the map (step 104). After that, the process returns to the beginning and the process is repeated. The vehicle position / azimuth calculation unit 6d calculates the position data and the traveling azimuth according to the following equations (1) to (3) based on the corrected vehicle current position and the traveling azimuth.

On the other hand, if the vehicle position and the traveling direction calculated by the vehicle position / direction calculating section 6d deviate greatly from the actual traveling road and the map matching becomes impossible, "NO" is determined in step 102. In such a case, the map matching processing unit 6e-2 uses the vehicle speed V measured by GPS.
It is judged whether the difference between the vehicle speed Vcs measured based on the output of gps and the self-contained navigation sensor 5 is less than a threshold value (step 10
5) If it is above the threshold, wait until it is below the threshold. If it is below the threshold value, GPS data (position data, azimuth data) stored in the data storage unit 6c
The current vehicle position and traveling azimuth are corrected based on the above, and the corrected current vehicle position and traveling azimuth data are input to the vehicle position / azimuth calculation unit 6d and the vehicle position mark generation unit 6f (step 106). In this way, the vehicle position and direction are corrected using GPS data only when the speed difference is less than or equal to the threshold value. This is because the GPS data is not located in the obstructed place, the receiving satellite is not switched and the SA is not switched, and the GPS data can be regarded as reliable.

In correcting the position and azimuth, the latest position data and azimuth obtained by GPS can be used as the current position and running azimuth of the vehicle. As for the traveling azimuth, the average value θ of the difference between the GPS azimuth θgps at a plurality of points where the speed difference is less than or equal to a threshold and the plurality of traveling azimuths θcs measured by the self-contained navigation at the same point
The following equation θoff = (1 / n) Σ (θgps−θcs) n can be calculated by the number of samples and corrected by adding the average angle θoff to the current traveling direction. The vehicle position mark generation unit 6f generates a vehicle position mark so as to be displayed on the corrected current vehicle position, and the map drawing control unit 6f
g reads the vehicle position mark data from the vehicle position mark generator 6f, inputs it to the display device 7, and displays it at the corrected position on the map (step 104). After that, the process returns to the beginning and the process is repeated. Although the present invention has been described above with reference to the embodiments, the present invention can be variously modified according to the gist of the present invention described in the claims, and the present invention does not exclude these.

[0017]

As described above, according to the present invention, when the map matching becomes impossible, the difference between the vehicle speed calculated using the position data obtained from GPS and the vehicle speed obtained from the distance sensor is obtained, and the difference is calculated. It is configured to determine whether it is less than a threshold value and correct the vehicle position and traveling direction using GPS position data and direction data when the speed difference is less than the threshold value. When it becomes impossible, the vehicle position and the traveling direction can be corrected by using the correct GPS position data and direction data.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a navigation system of the present invention.

FIG. 2 is an explanatory diagram of road layers in map information.

FIG. 3 is a configuration diagram of a GPS receiver.

FIG. 4 is a processing flow chart of map matching.

FIG. 5 is an explanatory diagram of position and azimuth calculation by self-contained navigation.

FIG. 6 is an explanatory diagram (1) of map matching by a projection method.

FIG. 7 is an explanatory diagram (2) of map matching by a projection method.

[Explanation of symbols]

 3 ... GPS receiver 5a ... Angle sensor 5b ... Distance sensor 6d ... Vehicle position / azimuth calculation unit 6e ... Vehicle position correction unit 6e-1 ... 6h ··· Speed difference monitoring unit 7 ··· Display device

Claims (1)

[Claims] 1. A map is drawn on a display screen based on map data, the vehicle position and traveling direction are measured by self-contained navigation to display a vehicle position mark on the map, and the vehicle position is displayed on the road by map matching. In the vehicle position correction method to correct, when map matching becomes impossible, it is determined whether the difference between the vehicle speed calculated using the position data obtained from GPS and the vehicle speed obtained from the self-contained navigation sensor is below a threshold value. The vehicle position correction method is characterized by correcting the vehicle position and the vehicle heading using GPS position data and heading data when the difference is less than or equal to a threshold value.