JP2859954B2 - Vehicle running position display method and device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method and an apparatus (vehicle-mounted navigation system) for displaying an image of a traveling position of a vehicle such as an automobile.

[Conventional technology]

In recent years, a computer calculates the traveling distance and traveling direction of a vehicle from signals from a vehicle speed sensor, a direction sensor, and the like, and estimates the current position of the traveling vehicle by matching the calculated traveling distance and traveling direction with road map data stored in advance. In-vehicle navigation systems for displaying are being developed.

As a prior art of this kind of navigation system, there are those disclosed in, for example, JP-A-61-243318 and JP-A-64-53112.

[Problems to be solved by the invention]

An important issue in in-vehicle navigation systems is how to accurately capture the current driving position.
However, simply integrating the sensor data (distance data, azimuth data) for each unit distance and calculating and updating the current position will result in an error between the road map stored as map road data and the actual road shape, the road traffic network, and the like. It has been difficult to accurately determine the current position due to the complexity of the sensor, sensor errors, and the like, and as the sensor data is accumulated, the data errors tend to increase and the accuracy of position display tends to deteriorate.

Therefore, conventionally, as disclosed in JP-A-64-53112, after an estimated position is obtained from sensor data such as a traveling distance and a traveling direction, each road (a road on the map data) corresponding to the estimated position is determined. A correlation coefficient is calculated, a road having a correlation coefficient with the smallest error is selected, and an estimated position on the selected road is displayed as a current position, or a road is disclosed in JP-A-61-243318. In this way, each pattern of the road on the map and the travel locus of the vehicle is divided into line segments and the pattern is recognized by polygon approximation, the road that seems to match the travel locus is selected, and the travel locus is displayed on this road, etc. Technology has been proposed.

Among these, the method of displaying the position by calculating the correlation coefficient of each road with respect to the estimated position as in the former, since the estimated position is captured microscopically per unit distance, the correlation coefficient of the road at the estimated position is Can be considered to be closer than the current actual route when viewed microscopically, and a position far from the actual route may be displayed.

In the latter case, since the respective patterns of the road on the map and the traveling trajectory of the vehicle are collated by the polygon approximation method, the estimated position can be captured from a wide field of view.
In this case as well, if there are a plurality of polygonally approximated roads at an approaching position, an incorrect route may be selected.

The present invention has been made in view of the above points, and an object of the present invention is to improve the reliability of an on-vehicle navigation system by accurately detecting a traveling position of a vehicle.

[Means for solving the problem]

The road map data may be significantly different from the actual shape due to digitizing errors (errors of road shapes on map drawing), old map versions, and the like. Considering traveling in such a place, rather than checking the similarity between local (microscopic) road data and sensor data for each unit distance, a so-called global (macro macro) for several links of the road is considered. If you check the similarity, you can grasp the exact current position without being confused by small errors. In addition, when there are a plurality of route plans that are relatively similar, it is desirable to take into account not only a global view but also a detailed judgment factor.

 The present invention is configured as follows in consideration of the above points.

The first means for solving the problem according to the present invention relates to the invention of the method, which comprises detecting a traveling distance and a traveling azimuth at each predetermined timing,
In a vehicle traveling position display method for displaying an image by matching the vehicle traveling position calculated from the detected data with the road map data stored in advance, (a) defining points of each route of the road map data and determining points between points; Are taken as links, and all possible route plans from the current position of the vehicle are extracted as selection candidates in a range of a predetermined number of links (the number of links of 2 or more) around a reference point, and (b) Further, the roads of the respective route plans are decomposed for each predetermined distance, and the angle of a vector connecting the start point and the end point of each decomposed element is calculated to obtain a road angle array for each route plan (a road angle array for each route plan). Are collectively referred to as a road angle array group). (C) On the other hand, the traveling locus of the vehicle is taken from the reference point and a predetermined distance is obtained. (The distance is the same as the distance when the roads of the respective route plans are decomposed) The angle of a vector connecting the start point and the end point of each decomposed element is calculated to obtain the angle array of the traveling trajectory. Calculate the angle difference between the road angle array for each route plan of the road angle array group and the travel locus angle array, select the route plan of the road angle array that is most similar to the travel locus angle array, and select the selected route plan. The traveling position calculated from the detection data of the traveling distance and the traveling direction is matched with the route plan and displayed as an image.

The second means for solving the problem is an invention relating to an apparatus, which is described in the first aspect.
The vehicle speed sensor 2 detects the traveling speed of the vehicle, the direction sensor 3 detects the traveling direction, and a road map data storage unit 4 that stores road map data.
A coordinate calculating means 6 for calculating two-dimensional coordinates indicating a vehicle traveling position based on the traveling distance per unit time obtained from the detection data of the vehicle speed sensor 2 and the detection data of the traveling azimuth sensor 3; The points of the route are determined, lines connecting the points are taken as links, and all possible route plans from the current position of the vehicle are within a predetermined number of links (the number of links of 2 or more) around the reference point with respect to the reference point. Angle calculation means A.7 for extracting all of the selected route plans as roads and further decomposing the extracted roads by a predetermined distance to calculate the angle of a vector connecting the start point and the end point of each decomposed element; and .7, a road angle array group data storage means 8 for storing the angle of each decomposition element calculated in step .7 as a data group of a road angle array for each route plan; Is decomposed for each predetermined distance (the same distance as when each route plan having the predetermined number of links is decomposed) is taken from the reference point, and the angle of the vector connecting the start point and the end point of each decomposition element is calculated. Calculating angle calculation means B.9
The travel trajectory angle array data storage means 10 for sequentially storing the angles of the decomposition elements calculated by the angle calculation means B.9 as a travel trajectory angle array, and a road angle array for each route plan of the road angle array group. A traveling route selecting means 11 for calculating an angle difference with the traveling locus angle array and selecting a route plan most similar to the traveling locus angle array; Image matching means 12 for matching the set coordinates
And an image display means 1 for displaying the output of the image matching means 12.

[Action]

Operation of First Problem Solving Means When using a navigation system, first, a road map near the current position is displayed as an image. A start point is specified on the road map as an initial current position, and this start point is an initial reference point S. Based on this, all conceivable route plans are extracted within a range of a predetermined number of links.

For example, in the example of FIG. 4, all possible route plans centered on the initial reference point S are listed as selection candidates within a range of two links. It becomes six like this. Here, the link is a line connecting the points defined on the road of each route plan. In addition to the reference point, where there is a characteristic of the road, for example, a corner, a branch point, an intersection, etc. of the road are selected. I do.

In FIG. 4, points S, 1 to 9 are regarded as points (points are defined for the entire range of the road map data), and points S-1, S-2, S-3, 1- 5,1−
6,2-7,3-4,3-8,3-9, etc. are links.

In the example of FIG. 4, the initial point S is a branch point, but is not limited to this, and may be any point as long as it is a start point. The point is to determine the range from which the road link is taken centering on this reference point S.

Then, the road of each route plan is further decomposed for each predetermined distance lcut. lcut is not necessarily a straight line.

As an example, FIG. 3 (1) shows the road link S-1-5 as one of the route plans.
FIG. 3B shows the road link S-1-5 decomposed for each lcut. Each decomposition element of this road is a vector indicating the distance and azimuth of lcut, and the angle of the vector connecting the start point and the end point of each decomposition element is calculated.

The angle of this road decomposition element can be represented by θr (k, l) (k, l = 0,1,2...). Here, k corresponds to the number of the proposed route, and increases by the number of road networks (routes). L corresponds to the number of road decompositions among the roads of a predetermined number of links, and l corresponds to the number of roads of the predetermined number of links. It increases as the link lengthens.

The angles θr (k, l) of these road decomposition elements are obtained as a road angle array for each route plan, and the angle arrays of the entire route plan are organized into a group (a group of road map data angle arrays) and stored. FIG. 6 shows a road angle array group corresponding to the route plan list in FIG. 5 as an example. In FIG. 6, “0”, “1”, and “2” below “road angle (ΔC)” are pointer values indicating the order of the decomposition elements. Further, the first pointer of the current search is displayed in the display field of “angle array pointer”.

On the other hand, when the vehicle travels, as shown in FIG. 7, the traveling locus is decomposed for every predetermined distance lcut based on S, and
As shown in the figure, the angular arrangement of the traveling locus is obtained.

FIG. 2A shows a traveling locus of the vehicle, where lcar (i) in each vector is a traveling distance per unit time obtained from, for example, an output of a vehicle speed sensor, and θcar (i) is an azimuth obtained by an azimuth sensor. (I = 0, 1, 2...).
Of course, each lcar (i) is not the same length. Therefore, as shown in FIG. 2 (2), the traveling locus is decomposed at a predetermined distance lcut. Then, as shown in FIG. 2 (3), the angle θs (j) of the vector connecting the start point and the end point of each of these decomposition elements
Are calculated (j = 0, 1, 2,...). These angles are sequentially stored as a travel locus angle array. FIG. 8 shows this travel locus angle array. The pointers in FIG. 8 indicate the order of the angular arrangement of the traveling locus.

The angle difference between the traveling locus angle array and each of the listed angle arrays of the road angle array group is compared, and a route plan related to the road angle array having the smallest angle difference is selected as the current traveling route ( The calculation of this angle difference will be described in detail in FIGS. 9 and 10 in the section of the embodiment).

Then, the vehicle traveling position (coordinates) calculated from the traveling direction and the traveling distance per unit time is matched with the selected route plan and displayed as an image.

Then, the next reference point S '(see FIG. 4) and the pointer are searched from the calculated current vehicle traveling position, and a series of operations similar to the above are repeated based on these.

According to such a vehicle travel position display method, it is possible to check the similarity between the vehicle travel trajectory and each network (route plan) of the road map data from a global perspective, and to provide microscopic details (direction of unit distance). Even if there is some error in
Without being confused, it is possible to select an accurate driving route, and when there are a plurality of approximated road routes on the map data, the decomposed elements (array elements) of each road data and the details of the traveling locus are different. Functions effectively as a judgment factor.

The second means for solving the problem relates to an apparatus used in the above method. The operation of the apparatus has been described in detail in the section of the embodiment.

〔Example〕

 An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration diagram showing an on-vehicle navigation system according to one embodiment of the present invention.

In FIG. 1, 1 is an image display means (liquid crystal display, CRT, etc.), 2 is a vehicle speed sensor, 3 is an azimuth sensor (for example, a geomagnetic sensor, an optical fiber gyroscope), and 4 is a compact disk (hereinafter referred to as a road map data). ,
5 is a control unit.

CD4 stores road map data. The road map data storage means may use an IC card or an IC memory instead of the CD4.

The control unit 5 includes a coordinate calculating means 6, an angle calculating means A.7, a road angle array group data storing means 8, an angle calculating means B.9, a traveling locus angle array data storing means 10, a traveling route selecting means 11, an image matching. It is constituted by means 12 and the like.

The functions of the elements 6 to 12 provided in the control unit 5 will be described in the navigation system operation described below.

When the navigation system is used when the vehicle is running, first, road map data near the current position is called up on the screen, and a point serving as an initial reference point is specified as a start point S from the data. A coordinate display means (not shown) such as a cursor is set at the start point S on the screen. S may be set at any start point.

When the initial reference point S is set, the angle calculation means A.
7 lists all possible route plans from the vicinity S of the current position of the vehicle as selection candidates in the range of, for example, two links (in the network of FIG. 4, as shown in FIG. -5, S-1-6, S-2-7, S-3-
4, S-3-8, S-3-9, a total of six route plans are listed), and each of the listed route plans NO1-N
The road O6 is further decomposed for each predetermined distance lcut (for example, 20 m) as shown in FIG. Then, the angle θr (k, l) of the vector connecting the start point and the end point of the road decomposition element of each route plan
Is calculated as shown in FIG. 2 (2) [refer to the meaning of θr (k, l) as described in the section of the operation of the invention]. As a road angle array in the order of pointers.

In these road angle arrays, all the route plans NO1 to NO6 are grouped together as a group, and the road angle array group data storage unit 8
Is stored.

When the vehicle travels under such condition settings, the coordinate calculating means 6 detects the traveling distance per unit time from the detection data of the vehicle speed sensor 2 and based on the traveling distance detection data and the detection data of the direction sensor 3. Then, two-dimensional coordinates indicating the estimated position (travel locus) of the vehicle travel are calculated. The data of the travel locus (travel position) is captured from the reference point S by the angle calculating means B.9, and is decomposed for each predetermined distance lcut as shown in FIG. 2,...) Are calculated from the vector θs (j) connecting the start point and the end point. And the angle θs
(J) travel locus angle array data is stored in the storage means 10 as a travel locus angle array group.

The traveling route selection means 11 is a pointer corresponding to the road angle array θr (k, l) and the traveling trajectory angle array θs (j) for each route plan in the road angle array group stored in the data storage means 8, 10. The angle difference between them is calculated, and a route plan in a road angle array that is most similar to the traveling locus angle array θs (j) is selected.

FIG. 9 shows the calculation data of the angle difference. In this embodiment, the road angle array θr of each of the route plans NO1 to NO6 is shown.
An angle difference for each decomposition element (pointer) between (k, l) and the travel path angle array θs (j) is calculated, and a total average value of the angle differences is calculated. Those are selected as route plans. This can be expressed by the following equation: error cost = sum of angle differences / number of road angle arrays. Referring to the angle difference calculation data in FIG. 9, the route with the smallest error cost is the route plan NO3.

Therefore, the route plan NO3 is selected as the traveling route, and the image matching means 12 matches the coordinates of the selected route plan with the coordinates calculated by the coordinate calculation means 6, and this is called by the image display means 1. Displayed above.

When the travel route is selected, the angle calculating means A.7 sets the reference point as the current location from the node S to the node S '.
Update to At the same time, angle calculation means B.9
Updates the traveling locus angle array pointer. That is, since the search was performed with the pointer values 0 to 2, the next search is set to start with the pointer value 3.

In this example, there is only one route plan with a small error cost, but there may be no route plan. In this case, the road angle array pointer is expanded by several, and the traveling trajectory angle array θs (j) is updated in accordance with this, and the angle between the updated traveling trajectory angle array and the road angle array of each route plan is updated. The difference is recalculated and the most approximate route plan is selected.

FIG. 10 shows an operation flowchart of the above navigation system.

In step 1, a possible road network (route plan) near the present location is divided into equal-interval lcuts to create a road angle array θr (k, l), and then a distance lcar (i) of the vehicle traveling locus per unit time. ), The azimuth θcar (i) is divided at equal intervals lcut to create a traveling trajectory angle array θs (j). Next, the error cost {θs (j) −θr (k, l)} / number of road angle arrays of the listed road network is calculated (step S3).

Then, a road route plan with the smallest error cost is selected. If the error costs are all large, the number of the sensor angle array pointers is increased or decreased by several, so that the smallest error cost is obtained.

Then, a road route plan with the lowest error cost is selected (step S4). Finally, a road angle array pointer for the next search is calculated (step S5).

〔The invention's effect〕

According to the present invention as described above, a global map matching method that does not cause a slight deviation of the road shape is adopted, and further, in selecting the road network, a microscopic (fine) road similarity is obtained. In addition, even if a plurality of similar road route plans exist, they can be accurately identified, and as a result, a highly reliable position display can be performed even if the accuracy of the map database is low.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main part of a vehicle traveling position display device (navigation system) according to one embodiment of the present invention, FIG. 2 is an explanatory diagram showing the principle of creating a traveling trajectory angle array, and FIG. FIG. 4 is an explanatory diagram showing an example of a road network, FIG. 5 is an explanatory diagram showing a route plan in which the road network of FIG. FIG. 6 is an explanatory diagram showing an angular arrangement as a result of decomposing the road network of FIG. 4 at equal distances, FIG. 7 is an explanatory diagram showing vector examples of data of a vehicle speed sensor and a direction sensor, and FIG. 8 is FIG. FIG. 9 is an explanatory diagram showing the result of calculating the angle difference between the road angle array and the traveling locus angle array for each route plan, and FIG. 1 shows the system operation of the embodiment of FIG. It is a flow chart. DESCRIPTION OF SYMBOLS 1 ... Image display means, 2 ... Vehicle speed sensor, 3 ... Direction sensor, 4 ... Road map data storage means, 5 ... Control unit, 6 ... Coordinate calculation means, 7, 9 ... Angle calculation means A , B, 8 ... road angle array group data storage means, 10 ...
... travel locus angle array data storage means, 11 ... travel route selection means, 12 ... image matching means.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G09B 29/10 G01C 21/00 G08G 1/0969

Claims (4)

(57) [Claims] 1. A method for detecting a travel distance and a travel azimuth at each predetermined timing, matching a travel position (coordinates) of a vehicle calculated from the detected data with road map data stored in advance, and displaying an image. (B) The points of each route in the road map data are determined, and lines connecting the points are taken as links,
All possible route plans from the current position of the vehicle are extracted as selection candidates within a predetermined number of links (two or more links) around a reference point, and (b) the roads of the respective route plans are further extracted. Each of the predetermined distances is decomposed, the angle of the vector connecting the start point and the end point of each decomposed element is calculated, and the road angle array for each route plan is obtained. (C) On the other hand, the traveling locus of the vehicle is taken from the reference point and decomposed at predetermined distances (the same distance as the decomposed element of the road of each route plan), and the start point and the end point of each decomposed element And (d) calculating the angle difference between the road angle array for each route plan of the road angle array group and the travel locus angle array, Selecting a route plan with a road angle array that is most similar to the trace angle array, matching the selected route plan with the vehicle traveling position calculated from the detection data of the traveling distance and the traveling azimuth, and displaying an image. Vehicle running position display method. 2. The method according to claim 1, wherein the selection of the route plan performed in the step (d) is performed by selecting an angle difference for each array element (decomposition element) between the road angle array and the travel trajectory angle array of each route plan. Is calculated, and the average value of the total angle difference between the two array elements is obtained, and the route plan of the road angle array having the smallest average value of the total angle difference is selected as the route plan most similar to the traveling locus angle array. A vehicle running position display method characterized by the above-mentioned. 3. The method according to claim 2, wherein the average value of the total angle difference between the array elements of both the road angle array and the travel trajectory angle array of each of the route plans is equal to or more than a predetermined value. While expanding the range of the proposed road angle array,
The traveling locus angle array is updated in accordance with this, the angle difference between the updated traveling locus angle array and the road angle array of each route plan is recalculated, and the road angle most similar to the traveling locus angle array is recalculated. A vehicle traveling position display method characterized by selecting a route plan in an array. 4. A vehicle speed sensor for detecting a traveling speed of a vehicle; an azimuth sensor for detecting a traveling direction; a road map data storage unit for storing road map data; Coordinate calculating means for calculating two-dimensional coordinates indicating the vehicle traveling position based on the detection data of the traveling distance and the traveling direction sensor; and determining a point of each route of the road map data and taking a line connecting the points as a link. In addition, all possible route plans from the current position of the vehicle are extracted as selection candidates in a range of a predetermined number of links (the number of links of 2 or more) around a reference point, and the roads of each extracted route plan are extracted. Further, an angle calculating means A for decomposing by a predetermined distance and calculating an angle of a vector connecting a start point and an end point of each decomposed element; Road angle array group data storage means for storing the angle of each decomposed element calculated in stage A as a data group of road angle array for each route plan; and a predetermined distance by capturing the traveling locus of the vehicle from the reference point. Angle calculating means B for decomposing each route (the same distance as when decomposing each route plan having the predetermined number of links) and calculating the angle of a vector connecting the start point and the end point of each decomposed element; A traveling locus angle array data storage means for sequentially storing the angles of the decomposed elements calculated in the above as a traveling locus angle array; and an angle difference between the road angle array and the traveling locus angle array for each route plan of the road angle array group. Traveling route selecting means for calculating a route plan of a road angle array that is most similar to the traveling locus angle array; and the coordinate calculating means for the road of the selected route plan. An image matching means for matching the calculated two-dimensional coordinates were, and image display means for displaying the output of said image matching means, vehicle running position display device characterized by comprising comprises.