JP2505934B2 - Vehicle position detection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle position detecting device for detecting the position of a vehicle. More specifically, the vehicle position is set by a map matching method, and the installation position from a beacon placed on the roadside or the like is set. The present invention relates to a vehicle position detection device that receives information and corrects vehicle position data.

[0002]

2. Description of the Related Art Conventionally, a so-called navigation device for providing a driver with current vehicle position information and the like has been mounted on a vehicle in order to assist the vehicle in reaching a destination. The navigation device includes a small computer and a display device, and detects the current position and traveling direction of the vehicle by a vehicle speed sensor, a direction sensor, etc., and displays this on the display device together with a road map and the like. is there.

However, in an apparatus for calculating an estimated position of a vehicle by so-called dead reckoning based on only the initial position of the vehicle and the outputs of the vehicle speed sensor and the direction sensor, the error which each of the above sensors necessarily has. Is accumulated as the travel distance increases, a large deviation occurs between the vehicle position displayed on the display device and the actual vehicle position, and the function inherent in the navigation device may be lost.

Considering these problems, and assuming that the vehicle travels on the road, all vehicles located within the range of the marginal error amount (vehicle existence probability area) centered on the estimated position of the vehicle. The estimated position of the vehicle is registered corresponding to the road, the correlation coefficient of each registered estimated vehicle position for each road is calculated, and the correlation coefficient indicating the smallest error for the road is selected and selected. There is known a map matching method that outputs the estimated position of the vehicle corresponding to the correlation coefficient as the current position of the vehicle (Japanese Patent Laid-Open Nos. 63-115004 and 63-115004).
63-148115, Japanese Patent Laid-Open No. 64-53112, Doi et al. "Development of vehicle position detection method for automobiles" Sumitomo Electric No. 137 pp.1
05-112, September 1990).

By using this map matching method, it is possible to detect a considerably accurate vehicle position based on the match with the road map pattern. On the other hand, in order to improve the position detection accuracy of the vehicle, conventionally, a roadside beacon is installed in the road traffic network, and a signal including the installation position information of the roadside beacon from this roadside beacon is placed in a relatively narrow range near the roadside beacon. A so-called roadside beacon that radiates and takes in this radiated signal from the antenna attached to the vehicle, extracts the above-mentioned installation position information from this captured signal, and corrects the vehicle position data with this installation position information to correct data A scheme has been proposed.

If this roadside beacon system is adopted, a more accurate vehicle position can be obtained as compared with the case where the vehicle position is detected only based on dead reckoning.

[0007]

In the conventional device, the installation position coordinates sent from the roadside beacon are
Although it was used as having no error, the installation position information sent from the roadside beacon has some problems in the installation condition and accuracy in measuring the installation position coordinates, and actually contains some error.

For this reason, although the accurate vehicle position is detected by the map matching method alone, the installation position information from the roadside beacon is adopted, which may rather increase the vehicle position detection error. Therefore, the present invention solves the above-mentioned technical problems, and in a vehicle position detection device that employs both the map matching method and the roadside beacon, the vehicle position is such that the current position data of the vehicle is corrected well. An object is to provide a detection device.

[0009]

According to a first aspect of the present invention, there is provided a vehicle position detecting device, wherein when the installation position information is received from the same beacon, the vehicle position setting means sets the installation position information at each reception time. A current position of the vehicle and a memory that stores the correlation coefficient when the current position of the vehicle is set, and beacon installation position correction means that corrects the installation position of the beacon using the information stored in this memory And is provided.

[0010]

According to the above construction, the installation position information is received every time the same beacon is passed, and the current position of the vehicle and the current position of the vehicle set by the map matching method at each reception time are set respectively. The correlation coefficient can be stored, and the stored data can be used to correct the beacon installation position coordinates. Therefore,
The vehicle position obtained based on the road map data can be corrected based on the more accurate beacon installation position coordinates.

[0011]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. FIG. 2 is a block diagram showing a navigation device incorporating a vehicle position detecting device. As shown in FIG. 2, the navigation device includes a display unit 2 and a console 1.
, A direction sensor 3, a distance sensor 4, a road map memory 5 storing road map data, and a road map memory 5
The memory drive 6 which reads the stored data from the memory, the traveling distance detected by the distance sensor 4 and the direction change amount detected by the direction sensor 3 are respectively integrated, and the integrated data and the road map data read by the memory drive 6 are integrated. Vehicle position detector 8 for detecting the vehicle position based on the comparison of
And reading a road map in a predetermined range, calculating an optimum route for guiding a vehicle, creating data for guidance display, controlling the voice output device 10, controlling the display 2, and detecting the vehicle position 8.
It has a navigation controller 9 for performing various controls such as the above, and a beacon receiver 11 for receiving radio waves from roadside beacons installed on the ground.

In more detail, the console 1 is
It has a key input board (not shown) for starting / stopping this device, running a cursor on the screen, scrolling a road map displayed on the screen, and the like. The display 2 has
A transparent touch panel is attached on the screen of a CRT, a liquid crystal panel, or the like. The display device 2 displays the initial setting menu supplied from the navigation controller 9,
By touching the display position on the screen by the driver, initial data such as the destination is input, and at the same time, the driver is prompted to display a directional screen at a road map or an intersection.

The road map memory 5 is composed of a large-capacity storage medium such as a CD-ROM, an IC memory card, and a memory such as a magnetic tape. The road map memory 5 divides a road map (including highway national roads, motorways, general national roads, major local roads, general prefectural roads, general city roads of designated cities, and other living roads) into a mesh. Road map data consisting of combinations of nodes and links in each mesh unit, along with a high-level map including data of highways (including highways, highways, general highways, and major local roads), along with highways It is stored separately as a lower hierarchical map including general roads such as general prefectural roads, general city roads of designated cities, and other non-main roads (hereinafter referred to as “general roads”).

Here, a node is generally a coordinate position for identifying an intersection or a bend of a road, and a node representing the intersection is an intersection node and a bend of the road (excluding the intersection). The represented node may be referred to as an interpolation point node. The node data includes an address of a node, an address of a node of an adjacent mesh that overlaps the node, an address of a link connected to the node, and the like.

A link is formed by connecting each intersection node. The link data includes the link address, the start and end node addresses of the link, the distance of the link, the direction in which the link passes, the required time data in that direction, the road type, the road width, one-way, right turn prohibited, left turn prohibited and toll It consists of traffic regulation data such as roads. However, traffic regulation data is complete for highways, but not for general roads.

The azimuth sensor 3 detects a change in azimuth as the vehicle travels, and a geomagnetic sensor, a gyro or the like can be used. The distance sensor 4 detects the traveling distance based on the speed of the vehicle, the number of rotations of the wheels, or the like, and a wheel speed sensor, a vehicle speed sensor, or the like can be used. The navigation controller 9 obtains the vehicle position information from the vehicle position detection unit 8 and displays the current vehicle position and the destination in an overlapping manner on the map, and calculates the optimum route from the current position to the destination by the Dijkstra method or the like. Have the function to do. In the Dijkstra method, the roads of the road map memory 5 to be calculated are divided into a number of points, the divided points are used as nodes, and the route connecting the nodes is used as a link. Assuming a tree of links from the start point to the end point with the node or link closest to the departure point as the end point, the link costs of all routes that make up the tree are sequentially added, and the most link reaching the start point is This is a method of selecting only a route with a low cost. Here are the items to consider when estimating the link cost: mileage, travel time, availability of highways, number of right and left turns,
There are traffic regulation information received by the beacon receiver 11 in addition to the running probability of the main road, avoidance of accident-prone zones, other items set according to the driver's preference, and the like.

Further, the navigation controller 9
Consists of a microcomputer, graphic processor, image processing memory, etc., menu screen display, map search, scale switching, scrolling, current vehicle position and direction display, destination and mark point display, purpose The direction and distance to the ground are displayed. The beacon receiver 11 incorporates installation position information, traffic regulation information, etc. from the roadside beacon.

The vehicle position detection unit 8 integrates the distance data detected by the distance sensor 4 and the azimuth change data detected by the azimuth sensor 3 to calculate traveling locus data, and the traveling locus data and the road map memory. The vehicle position on the road that considers the existence probability of the vehicle is detected based on the comparison with the road pattern stored in 5 (the so-called map matching method). The vehicle position is appropriately corrected using the obtained data regarding the estimated position of the vehicle, and the final vehicle position and direction of the vehicle are output.

The functional blocks of the vehicle position detector 8 are shown in FIG. The input preprocessing unit 22 inputs the azimuth data sampled from the azimuth sensor 3 and the distance data sampled from the distance sensor 4, and performs calibration and filtering to obtain the optimum estimated azimuth. The current position estimation unit 23 calculates an estimated vehicle position by dead reckoning from the optimum estimated azimuth and distance data obtained from the input preprocessing unit 22, and
The corrected current vehicle position obtained from the vehicle position reset unit is taken in and the estimated vehicle position is updated. The traveling road estimating unit 24 obtains a vehicle existence probability region centered on the obtained estimated vehicle position, and repeatedly calculates a correlation coefficient γ between the road network data obtained from the road map memory 5 and the estimated vehicle position, The vehicle position on the link included in the vehicle existence probability area is calculated. Here, the vehicle existence probability area refers to an area (for example, a circle centered on the vehicle position) in which the vehicle existence probability is equal to or higher than a certain place, which is determined by the accuracy of the vehicle position estimation method. Vehicle position reset unit 2
5 corrects the estimated vehicle position using the vehicle position obtained by the above method. The position of the vehicle thus corrected using the map matching method is represented by β below.

By the way, the horizontal axis represents the vehicle position error between the estimated vehicle position obtained from the current position estimation unit 23 and the actual vehicle position, and the correlation coefficient γ with the road network data is calculated based on the estimated vehicle position. Then, if the vertical axis is the probability that the vehicle position matches the link, the correlation as shown in FIG. 4 is obtained. That is, when the vehicle position error is small, the optimum vehicle position β can be reliably obtained on the link while the vehicle is traveling for a while and the correlation coefficient γ between the estimated vehicle position and the road pattern is repeatedly calculated. In other words, the vehicle position can be narrowed down on a specific link. This state is called "road detection state". On the other hand, if the vehicle position error becomes large, the probability that the vehicle position can be narrowed down to a specific link will decrease even if the correlation coefficient γ with the road pattern is calculated, and the vehicle position error will increase considerably. When it becomes larger (points of e or more in FIG. 4), matching with the road cannot be obtained no matter how many times the correlation coefficient γ is calculated. In this case, the position of the vehicle cannot be found on the road. This state is called "road non-detection state". In this case, the vehicle position reset unit 25 cannot correct the estimated vehicle position, so the vehicle position output unit 2
The vehicle position output from 6 remains the vehicle position estimated by dead reckoning.

Further, when the beacon receiver 11 acquires the position signal, the management judgment unit 21 further acquires the position coordinates αi (i is a subscript given to each beacon) acquired by the beacon receiver 11 and the beacon receiver 11 The position coordinates βij of the vehicle corrected using the map matching method at the time when the position coordinates αi are acquired from (j is a subscript given at each time when the position coordinates αi is acquired, j = 1,2, ..., n), The correlation coefficient γij at that time and the number n of times the position coordinates αi are acquired are stored in the memory 27, and the predicted position <Pi> of the beacon is calculated using the information stored in this memory 27 (at this time, Functioning as a beacon installation position correcting means), if necessary, the predicted position <Pi> is used to correct the vehicle position, and the corrected vehicle position is used as the current position estimation unit 2
Return to 3. In this way, the management determination unit 21 outputs the corrected vehicle position to the navigation controller 9.

The vehicle position correction process of the management judgment unit 21 will be described with reference to the flowchart (FIG. 1).
First, the management determination unit 21 determines whether the beacon receiver 11 has acquired a position signal (step S1),
When the position signal is acquired by the beacon receiver 11, the position coordinates αi acquired by the beacon receiver 11, the position coordinates βij of the vehicle corrected by the map matching method at that time point, and the correlation coefficient γij at that time point are Memory 27
In the table (step S2). The structure of this table is shown in Table 1.

[0023]

[Table 1]

The first column of Table 1 stores the position coordinates α acquired by the beacon receiver 11 for each beacon identified based on the beacon identification information included in the beacon position signal. For example, the position coordinate α1 of the first beacon is stored in the first area, and the position coordinate αi of the i-th beacon is stored in the i-th area. The second column stores the vehicle position coordinates β obtained by the map matching method at the time of receiving beacon information, for each beacon and for each number of times of beacon signal reception. For example, the vehicle position coordinates β11, β1 at each time when the position coordinate α1 of the first beacon is obtained
2, ... in the first area, vehicle position coordinates βi1, βi at each time when the position coordinate αi of the i-th beacon is obtained
2, ... are stored in the i-th area. Further, in the third column, the correlation coefficient γ obtained at the same time is stored for each beacon and for each number of times of beacon signal reception. For example, the correlation coefficients γ11, γ12, ... At each time when the position coordinate α1 of the first beacon is obtained are set in the first area as the i-th
The correlation coefficients γi1, γi2, ... At each time when the position coordinate αi of the th beacon is obtained are stored in the ith area. Further, in the fourth column, the number of times of beacon signal reception n1, n2, ... Is stored for each beacon. As mentioned above,
Each time the same beacon is passed through the table, the information about that beacon is stored, so a non-volatile memory is naturally used as the memory 27.

When the storage is finished, the management judgment unit 21 calculates the predicted position <Pi> of the beacon (step S3). The predicted position <Pi> of the beacon is appropriate while comparing the position coordinates αi of the beacon received from the beacon with the position coordinates of the vehicle obtained by the map matching method and evaluating the certainty factor of the map matching method. It is a weighted average operation. That is, the predicted position <Pi> when passing through a specific beacon is expressed by the function <Pi> = f (αi, βij, γij, ni) (j = 1,2, ..., n
i) required. The characteristic of the function f is that the average value Σγij / ni [j = 1,2, ..., ni] of the correlation coefficient per one pass of the beacon is large, that is, the higher the certainty of the map matching is, the more weight is given to the vehicle position coordinate βij. It is set to be heavier, and the lower the certainty factor of the map matching is, the lighter the weight for the vehicle position coordinate βij is set. The specific example of the function f is as follows.

F = (1−Σγij / ni) αi + (Σγij / ni) βi In step S4, it is determined whether or not the position correction by the predicted position <Pi> is necessary. This judgment criterion is, for example, whether or not the distance between the predicted position <Pi> and that detected by map matching is very close (for example, 2
Within 0 m).

If it is necessary to correct the position based on the predicted position <Pi>, the installation position of the beacon is corrected in step S5. As described above, in the embodiment, the positional information sent from the beacon, the positional coordinates of the vehicle obtained by the map matching method stored when the beacon was received and when the beacon was previously passed and the phase relationship at that time Since it is evaluated and corrected based on the number and used as a more accurate predicted position <Pi>, it is possible to correct the error in the beacon position coordinate α due to the beacon installation conditions, etc. Can be corrected more accurately.

The present invention is not limited to the above-described embodiment, and for example, the vehicle position coordinates β obtained by the map matching method at the time of receiving beacon information in the table of the memory 27 and the phase obtained at the same time. When storing the relation number γ,
If the correlation coefficient γ is stored only when the correlation coefficient γ is a certain value or more, the storage capacity can be reduced. If the predicted position <Pi> calculated last time is stored in the table, the vehicle position coordinates β and the correlation coefficient γ before the calculation of the predicted position <Pi> can be deleted from the storage. The memory capacity can be reduced.

[0029]

As described above, according to the vehicle position detecting apparatus of the present invention, the vehicle position obtained based on the map data has a high certainty factor (a large correlation coefficient and reception). It can be used to correct the installation position coordinates of the beacon, depending on the number of times), so that the installation position coordinates of the beacon can be evaluated more accurately. Therefore, the vehicle position obtained based on the road map data can be corrected on the basis of the more accurate beacon installation position coordinates, and the more accurate vehicle position can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing a process of correcting a beacon installation position coordinate.

FIG. 2 is a block diagram of a navigation device.

FIG. 3 is a block diagram of a vehicle position detection unit forming a part of the navigation device.

FIG. 4 is a graph showing a road matching probability.

[Explanation of symbols]

 3 azimuth sensor 4 distance sensor 5 road map memory 8 vehicle position detection unit 11 beacon receiver 21 management determination unit 27 memory

Continuation of the front page (56) Reference JP-A 63-115004 (JP, A) JP-A 4-99910 (JP, A) JP-A 62-297999 (JP, A) JP-A 58-119238 (JP , A) JP-A-1-181239 (JP, A) JP-A-63-219100 (JP, A)

Claims (1)

(57) [Claims] 1. A road map memory storing a road map, a traveling distance detecting means for detecting a traveling distance of a vehicle, an azimuth detecting means for detecting an azimuth of the vehicle, and a traveling distance and an azimuth of the vehicle at predetermined timings. Based on the vehicle position estimation means that obtains and integrates and detects the estimated position of the vehicle based on this integrated data, and the road map stored in the road map memory, the position in the vehicle existence probability region centered on the estimated position of the vehicle Select all the roads to be calculated, calculate the correlation coefficient between the change of the estimated vehicle position and each road pattern, and register the road having a correlation coefficient of a certain value or more as a candidate road, among the registered candidate roads,
From the vehicle position setting means that specifies the road with the most current correlation coefficient and sets the current position of the vehicle on that road, and the beacon that is installed on the road and emits a radio signal containing the installation position information In a vehicle position detecting device having a receiving means for receiving position information and a vehicle position correcting means for correcting the current position of the vehicle based on the installation position information received by the receiving means, the installation position information is received from the same beacon. In this case, a memory for storing the current position of the vehicle set by the vehicle position setting means at each reception time and a correlation coefficient when the current position of the vehicle is set, and information stored in this memory are used. And a beacon installation position correction means for correcting the installation position of the beacon.