JP2001349738A - Navigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct a vehicle position to a correct position on a road, even in a road branched with a very small angle such as an IC and a JCT in a highway. SOLUTION: The first map matching processing part 20a finds the optimum road by map matching processing MM1, and corrects the vehicle position on the optimum road to be treated as an actual vehicle position, the matching processing part 20b finds the optimum road by map matching processing MM2, and corrects the vehicle position on the optimum road to be treated as a temporary vehicle position. The processing MM1 and the processing MM2 are executed in parallel thereafter, and the vehicle position is corrected using the temporary vehicle position as the actual vehicle position, when a road to be map- matched is not found in the map matching processing MM1, or when the road is branched at the very small angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device, and more particularly to a navigation device that corrects a vehicle position by performing a map matching process using a self-contained navigation sensor.

[0002]

2. Description of the Related Art A navigation device which provides guidance of a vehicle and enables a driver to easily arrive at a desired destination is detected by detecting the current position of the vehicle and using a DVD-ROM.
Read the map data near the vehicle position from the storage medium such as, and display the map image on the display screen,
The vehicle position mark is superimposed and displayed on a predetermined location on the map image. Then, as the current position changes due to the movement of the own vehicle, the own vehicle position mark on the screen is moved, or the own vehicle position mark is fixed at a predetermined position such as the center of the screen, and the map is scrolled. The map information near the car position can be understood at a glance.

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

There are two methods of detecting the vehicle position: dead reckoning navigation (self-contained navigation), which determines the vehicle position cumulatively from the departure point using a direction sensor and a distance sensor, and absolute detection based on the principle of triangulation using satellites. There is satellite navigation to find the position of the vehicle. Of these, dead reckoning navigation is simple in configuration, and ensures reliable vehicle positioning even when traveling in tunnels where satellite radio waves do not reach or in urban areas where satellite radio waves are blocked by buildings or multiple reflections are not available. Although it has the advantage of being able to be detected, the accuracy of detection is poor because sensor errors and errors due to meandering of the vehicle accumulate, and especially when the mileage is long, the error becomes too large and the vehicle position mark is located far from the actual position. Is displayed.

[0005] For this reason, in the navigation device, road data for map matching is included in the map data so that the vehicle position detected by dead reckoning can be corrected using the road data. For map matching,
A projection method that projects the vehicle position obtained by dead reckoning on the nearest road in the road data to correct the vehicle position mark on the correct road, and a moving locus of the vehicle position obtained by dead reckoning and the road shape in the road data There are two pattern matching methods for searching for a correct road on which the vehicle is traveling by comparing the roads and correcting the road.

FIG. 9 is an explanatory diagram of a vehicle position correcting method using a pattern matching method. In addition, the vehicle is moved the road RD ₁ in the north-east of direction, to change the course to the east was out on the road RD _2, when it reached the point Pc of the road RD ₃ turn to the north at the point Px, vehicle position mark CM Is displayed on the point Pc ′, and the traveling locus RTD is indicated by a dotted line. In the pattern matching method, every time the vehicle travels a predetermined distance (for example, 200 m), (1) road data having the same shape as the shape of the travel locus RTD is searched using map data, and (2) a reference point, for example, the latest node Px And find a point Pc on the road data RD such that Px′Pc ′ = PxPc,
(3) After that, the vehicle position mark CM is moved to the point Pc ′.
To the point Pc. According to this map matching process, the vehicle position can be corrected to the correct position even if there is an error in the sensor or the vehicle travels in a meandering direction and the traveling distance has an error.

[0007]

However, the vehicle shown in FIG.
As shown in the figure, roads RD ₃ and RD ₄ divided at a small angle
When there is road data with a road shape similar to the travel locus, such as when traveling in one direction, it is not possible to determine which road data to correct the vehicle position, and incorrect There is a problem that a vehicle position and a running locus are displayed on a road. In particular, on a road that branches at a small angle, such as an IC on a highway or a JCT, a mismatch easily occurs because there is almost no difference in the road shapes before and after the branch point. This problem similarly occurs when map matching is performed by the projection method. Accordingly, an object of the present invention is to provide a navigation device that can detect the current position of a vehicle or the road on which the vehicle is traveling without errors.

[0008]

According to the present invention, there is provided a navigation apparatus for correcting a vehicle position by performing a map matching process using a self-contained navigation sensor to calculate an estimated vehicle position. Position calculating means, candidate road detecting means for detecting a candidate road from the estimated vehicle position, running locus storage means for storing a running locus of the vehicle, map data storing means for storing map data, A small angle branch detecting means for detecting branching at an angle, and a vehicle running locus shape stored in the running locus storage means and the candidate road detecting means when a small angle branch is detected by the small angle branch detecting means. The vehicle position correction for collating the detected candidate road shapes and correcting the estimated vehicle position on the optimum road with the candidate road having the closest shape as the optimum road. It is characterized in that it comprises a means.

[0009]

(A) Navigation system (a) Overall configuration FIG. 1 is an overall configuration diagram of a navigation system.
1 is a navigation control device, 2 is an operation unit (for example, a remote controller) for inputting various commands to the navigation control device 1, setting a guidance route, setting various data, etc., 3 is a map, a guidance route, an intersection guide map, A display device for displaying menus and the like, 4 a ROM disk for storing map information, 5 a ROM disk drive, 6
Is a GPS receiver that receives the radio waves from the satellites and measures the current position and bearing of the vehicle, 7 is an antenna that receives the radio waves from each satellite, 8 is a self-contained navigation sensor, and 9 is a guidance voice at the intersection This is an audio unit that can use a car audio device.

The GPS receiver 6 has three-dimensional positioning or two-dimensional positioning.
The vehicle position and direction are calculated by performing dimensional positioning processing (direction is the direction connecting the current vehicle position and the vehicle position one sampling time ΔT ago), and these are output together with the positioning time. The self-contained navigation sensor 8 includes a relative direction sensor (angle sensor) such as a vibrating gyroscope that detects the rotation angle of the vehicle, not shown, and a distance sensor that generates one pulse for each predetermined traveling distance.

(B) Configuration of ROM Disk The map information stored in the ROM disk 4 includes (1) a road layer, (2) a background layer for displaying objects on a map, and (3) names of municipalities. A character layer for displaying characters, and (4) IIS (Integrated Information Serv).
ice) It is composed of an IIS layer for storing information. The road layer has road link data RLDT, node data NDDT, and intersection data CRDT as shown in FIG. Road link data RLDT
Gives the attribute information of the road. The total number of nodes on the road link, the number of each node constituting the road, the road number (road name), and the type of road (national road, expressway, prefectural road, and others) And so on. The intersection data CRDT is, for each intersection on the map, a set of nodes closest to the intersection (referred to as an intersection configuration node) among the nodes on the link connected to the intersection, and the node data NDDT forms a road. This is a list of all nodes, and includes position information (longitude and latitude) for each node, pointers to intersection data if the node is an intersection, and pointers to road links to which the node belongs if the node is not an intersection.

(B) Navigation control device FIG. 3 is a block diagram of the navigation control device. 1 is a navigation control device, 2 is a remote controller, 3 is a display device, 4 is a ROM disk for storing map information, and 5 is a ROM disk. A drive, 6 is a GPS receiver, 7 is an antenna, 8 is a self-contained navigation sensor, 9 is an audio unit, and a self-contained navigation sensor 8 is a relative direction sensor (angle sensor) 8 such as a vibrating gyro for detecting a vehicle rotation angle.
a, a distance sensor 8b that generates one pulse for each predetermined traveling distance.

In the navigation control device 1, 11
Is a map readout control unit, which is a focus position (longitude / latitude position at the center of the screen) when a map movement operation or a map selection operation is performed using a joystick key, a map reduction / enlargement key, or the like.
Is calculated, and the ROM disk drive 5 is controlled based on the own vehicle position or the focus position, etc.
It reads predetermined map information from the M disk 4. Reference numeral 12 denotes a map buffer for storing map information read from the ROM disk 4. The map buffer 12 reads a plurality of map information (a plurality of units) around the own vehicle position or the focus position, for example, map information of 3 × 3 units so that the map can be scrolled. 13
Is a map drawing unit that generates a map image using map information stored in the map buffer 12, 14 is a VRAM that stores the map image, and 15 is based on a screen center position (own vehicle position, focus position). The read control unit changes the position of one screen cut out from the VRAM 14 and scrolls and displays the map according to the movement of the vehicle position or the focus movement.

Reference numeral 16 denotes an intersection guide unit which provides guidance at an approaching intersection by a display image and voice when the vehicle approaches within a predetermined distance from the approaching intersection at the time of actual route guidance. Enlarged intersection, destination,
A traveling direction arrow, etc.) is displayed on the display screen, and the traveling direction is guided by voice. Reference numeral 17 denotes a remote control unit that receives a signal corresponding to the operation of the remote controller and instructs each unit.
A G 18 stores GPS data from the GPS receiver 6.
A PS data storage unit, 19 is a vehicle position / azimuth calculation unit that calculates a vehicle position (estimated vehicle position) and a vehicle azimuth based on the self-contained navigation sensor output, and 20 is a map matching control unit, which has the following functions. I have.

The first function is to perform a map matching process for each predetermined traveling distance using the map information read from the map buffer 12, the estimated vehicle position, and the vehicle azimuth to determine the position of the vehicle on the traveling road. This is the original function to correct. In self-contained navigation, errors accumulate as the vehicle travels, and the vehicle position deviates from the traveling road. Therefore, the map matching control unit 20 corrects the estimated vehicle position on the traveling road. If the vehicle position deviates greatly from the road due to an error in the self-contained navigation, and the vehicle position cannot be map-matched to the actual position on the actual road, the map matching control unit 20 outputs the position data (GPS) obtained from the GPS.
Position) and azimuth data (GPS azimuth) to correct the own vehicle position and vehicle azimuth by self-contained navigation. That is, the map matching control unit 20 calculates a distance D between the GPS position and the self-contained navigation position, compares the distance D with a predetermined distance threshold Dth (for example, 150 m), and obtains D> D
In the case of th, the own vehicle position is corrected by the GPS data, and the vehicle position mark is put on the road by a map matching process performed thereafter. The second function is that when detecting that the road branches at a small angle (small angle), the map matching process before and after the branch point is narrowed down to a short distance, and the estimated vehicle position is corrected on the traveling road. This is a function of the present invention and will be described later.

A guidance route control unit 21 calculates the guidance route to the input destination, and when the vehicle deviates from the guidance route (off-route), regenerates the guidance route from the current vehicle position to the destination. The one that performs calculation processing, 22 is a guidance route memory that stores guidance routes, and 23 is a guidance route drawing unit.
The guidance route memory 22 stores all nodes N on the guidance route IRT (see FIG. 4) calculated by the guidance route control unit 21.
Position data of s, Ni (i = 1, 2,...), and No are stored from the starting point to the destination as shown in FIG. During traveling, the guide route drawing unit 23 reads out guide route information (node sequence) from the guide route memory 22 and draws it on a map.
An operation screen generator 24 displays various menu screens (operation screens), a mark generator 25 displays various marks such as a vehicle position mark and a cursor, and an image synthesizer 26.

(C) Configuration of Map Matching Control Unit (a) Configuration FIG. 6 is a configuration diagram of a vehicle position / azimuth calculation unit and a map matching control unit, 19 is a vehicle position / azimuth calculation unit, and 20 is map matching control. Department. 19a and 19b are changes Δ of the vehicle position and the vehicle direction from the self-contained navigation sensor 8.
Mainly calculating and outputting estimated vehicle positions X, Y; X ′, Y ′ and vehicle directions θ, θ ′ based on the own vehicle position and the vehicle direction fed back from X, ΔY, Δθ and the map matching control unit 20. , And sub-first and second estimated vehicle position calculators. In the map matching control unit 20, reference numeral 20a denotes a map matching process (MM
The first map matching processing unit 20b that performs 1) performs a map matching process (MM
This is a second map matching processing unit that performs 2).

Normally, the map matching control unit 20 includes a map matching process MM1 and a second map matching process unit 20b by the first map matching process unit 20a.
MM2 is performed in parallel. That is, the estimated vehicle position is corrected on the candidate road obtained by the map matching process MM1 and regarded as the actual vehicle position, and the estimated vehicle position is corrected on the optimum road obtained by the map matching process MM2 and the temporary vehicle is corrected. A map matching process for the position is executed. Then, when a predetermined condition (described later) by the first map matching processing unit 20a is satisfied, the second map matching processing unit 20a
The temporary vehicle position obtained in b is set as the actual vehicle position. 2
0c is a traveling locus storage unit for storing a locus of the vehicle traveling for each predetermined distance, 20d is an actual vehicle position correction processing unit, and a second map matching processing unit 20b when a predetermined condition is satisfied.
Is used as the actual vehicle position.

In the first map matching processing section 20a, reference numeral 31 denotes a candidate road search section for searching a map data for a candidate road to be subjected to map matching, and performs the following processing. First, a link which is included in a 200 m square around the estimated vehicle position and which can descend a vertical line, the angle between the vehicle direction and the link at the estimated vehicle position is within a certain value (for example, 45 °), and The length of the perpendicular dropped from the estimated vehicle position to the link is a certain distance (for example, 1
00m). Next, the following equation Z = dL × α + dθ × β (1) is applied to each of the obtained links to calculate the candidate coefficient Z. In addition, dL is the length of the perpendicular from the estimated vehicle position to the link (the distance from the estimated vehicle position to the link), dθ is the angle between the estimated vehicle direction and the link, α is the distance coefficient, and β is the angle coefficient. The link with the smallest value of the candidate coefficient Z is set as the optimal road. Reference numeral 32 denotes a vehicle position correction unit that corrects the estimated vehicle position calculated by the estimated vehicle position calculation unit 19a to a position on an optimal road, and 33 denotes an actual vehicle position storage unit that stores the corrected vehicle position as an actual vehicle position. And 34, a small angle branch detection unit for detecting that there is a candidate road branching at a small angle.

In the second map matching processing unit 20b, a reference 41 searches the map data for a candidate road having the same shape as the vehicle travel locus stored in the travel locus storage unit 20c, and determines the closest road as the optimal road. When a small-angle branch is detected by the small-angle branch detection unit 34, the section (distance) before and after the branch point is narrowed to a section (distance) shorter than usual to improve the detection accuracy, and is optimal. This is to search for roads. 42 is an estimated vehicle position calculating unit 19b
A vehicle position correction unit 43 that corrects the estimated vehicle position calculated by the above to a position on the optimum road, and 43 is a temporary vehicle position storage unit that stores the corrected vehicle position as a temporary vehicle position.

(B) Small-angle branch detection processing FIG. 7 is a flowchart of the small-angle branch detection processing. The small angle branch detection unit 34 determines whether there are two or more candidate roads in the map matching process of the first map matching processing unit 20a (step 101), and determines that there is no small angle branch if there is no such road (step 101). Step 102). On the other hand, if there are two or more candidate roads, the difference between the candidate coefficients Z of the first and second candidate roads is calculated using equation (1), and it is determined whether or not the difference is equal to or less than the set value (step 103), if it is larger than the set value, it is determined that the small angle branch is not performed (step 10).
2). However, if the difference between the obtained candidate coefficients Z is equal to or less than the set value, it is determined that the first candidate road and the second candidate road are branched at a small angle from each other, and the candidate road of the second map matching processing unit 20b is determined. A detection signal is output to the search unit 41 (Step 104).

(C) Map Matching Process When Detecting a Small Angle Branch FIG. 8 is a flowchart of the map matching process when detecting a small angle branch. In the map matching (pattern matching) processing of the second map matching processing unit 20b, the candidate road search unit 41 uses the first map matching processing unit 20
It is monitored whether or not there is a detection signal from the small angle branch detection unit 34 (step a). If there is a detection signal of a small angle branch, the vehicle travel locus shape stored in the travel locus storage unit 20c is narrowed down to a short section (for example, 10 m) and the candidate road shape of the map data is compared (step 20).
2) The candidate road closest to the travel locus shape among the candidate road shapes is set as the optimum road (step 203). The vehicle position correction unit 42 corrects the estimated vehicle position calculated by the estimated vehicle position calculation unit 19b to a position on the optimum road (Step 204). The temporary vehicle position storage unit 43 stores the corrected vehicle position as a temporary vehicle position (Step 205).
When there is no detection signal of a small angle branch, a normal pattern matching process is performed in a normal section in which the shape of the traveling locus is compared with the candidate road shape of the map data.

(D) Processing for Correcting the Temporary Vehicle Position to the Actual Vehicle Position Normally, the map matching processing (MM1) is continued assuming that the vehicle is traveling on the optimal road obtained by the map matching processing (MM1). The actual vehicle position correction processing unit 20d performs not only when the candidate road cannot be obtained in the map matching process (MM1),
The temporary vehicle position obtained by the second map matching process (MM2) is also corrected to the actual vehicle position when a small angle branch is detected. As a result, the navigation device can increase the accuracy of the map matching process on a road that branches at a small angle, and can correct the vehicle position recognized by the navigation device to the actual vehicle position on the correct road. it can.

The present invention has been described with reference to the embodiments.
The present invention can be variously modified in accordance with the gist of the present invention described in the claims, and the present invention does not exclude these.

[0025]

As described above, according to the present invention, when a candidate road branching at a small angle is detected in the map matching process, the shape of the traveling locus is compared with the shape of the candidate road. Accuracy can be increased, and the vehicle position recognized by the navigation device can be corrected to a correct actual vehicle position on the road.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a navigation system.

FIG. 2 is an explanatory diagram of a configuration of road data in map data.

FIG. 3 is a configuration diagram of a navigation control device.

FIG. 4 is an explanatory diagram of a node array forming a guidance route.

FIG. 5 is an explanatory diagram of guidance route data stored in a guidance route memory.

FIG. 6 is a configuration diagram of a map matching control unit.

FIG. 7 is a flowchart of a small angle branch detection process.

FIG. 8 is a flowchart of a map matching process when detecting a small angle branch.

FIG. 9 is an explanatory diagram of a conventional pattern matching method.

FIG. 10 is an explanatory diagram showing a problem of the conventional method.

[Explanation of symbols]

 19: vehicle position / direction calculation unit 20: map matching control unit 20a: first map matching processing unit 20b: second map matching processing unit 20c: travel locus storage unit 20d: actual vehicle position correction Processing unit 34 ... Small angle branch detection unit

Claims (1)

[Claims] 1. A navigation device for correcting a vehicle position by performing a map matching process using a self-contained navigation sensor, an estimated vehicle position calculating means for calculating an estimated position of a vehicle, and detecting a candidate road from the estimated vehicle position. Candidate road detecting means, running locus storing means for storing a running locus of the vehicle, map data storing means for storing map data, and a small angle branch detecting means for detecting that the candidate road branches at a small angle; When the small angle branch is detected by the small angle branch detection means, the vehicle travel locus shape stored in the travel locus storage means is compared with the candidate road shape detected by the candidate road detection means, and the candidate having the closest shape is checked. Vehicle position correcting means for correcting the estimated vehicle position on the optimum road with the road as the optimum road. Device.