WO2009008611A2

WO2009008611A2 - Map matching method in crossroad and navigation system

Info

Publication number: WO2009008611A2
Application number: PCT/KR2008/003768
Authority: WO
Inventors: Sang Hun Chang
Original assignee: Thinkware Systems Corporation
Priority date: 2007-07-10
Filing date: 2008-06-28
Publication date: 2009-01-15
Also published as: KR20090005703A; WO2009008611A3

Abstract

Disclosed is a map matching method in an intersection and a navigation system. The map matching method includes searching for a route to a destination set by a user and applying a predetermined curvilinear rate to map matching data used for turning guidance, when an intersection is sensed while driving along the retrieved route.

Description

MAP MATCHING METHOD IN CROSSROAD AND NAVIGATION SYSTEM

Technical Field

The present invention relates to a navigation system, and more particularly to a map matching method and a navigation system which can perform map matching of a route including a location of a vehicle to map data, and thereby can provide guidance about a driving direction at an intersection.

Background Art Generally, a navigation system is a system to provide navigation information for driving of vehicles, such as cars, using an artificial satellite. The navigation system is referred to as an automatic navigation system.

The navigation system equips a Global Positioning System (GPS) module, and thereby can receive predetermined data from a GPS satellite in orbit above the earth, and calculate a location of a vehicle based on the received data. The navigation system performs map matching of the calculated location of the vehicle with previously stored map data and uses the same as basic material to provide a map and location guidance. Particularly, the navigation system searches for a route from a current location of the vehicle to a destination set by a user to provide a route guidance service according to the retrieved route.

Also, since the calculated location of the vehicle outputted from the GPS module may be off by dozens of meters, when the calculated location of the vehicle is off a road of map data, the navigation system adjusts the location of the vehicle by compulsorily moving the location of the vehicle to a road nearest to the vehicle using map matching.

The route guidance service searches for a guidance object, such as an intersection, underground passage, overpass, entrance of an expressway, and the like (hereinafter, the guidance object is referred to as an intersection) and provides guidance to turn and information about a direction at the corresponding intersection, when the intersection is determined.

FIG. 1 illustrates an example of an intersection which shows an actual driving route (P) of a vehicle in an intersection and corresponding map matching data (M) of an existing navigation terminal.

Generally, a system based on navigation extracts a central line of a road, which has a certain width, to use the extracted central line as a road and extract an intersection point where central lines of roads intersect to use the extracted intersection point as an intersection.

Disclosure of Invention Technical Goals

In actuality, a turn of a driven vehicle in an intersection where a certain width exists is made in a curve. However, since a logical road shape in an existing navigation system with respect to right turn and left turn are in a right angle-shape, there has been difficulty in providing natural driving guidance.

That is, as illustrated in FIG. 1, a real driving route (P) of a vehicle in an intersection may be in a curve, however, since route guidance service in the navigation system performs map matching based on a central line of a road (L), the route guidance service expresses a route in a straight line according to a map matching data (M).

The existing navigation system has a problem in that it expresses a map unnaturally when providing turning guidance in an intersection, thereby decreasing customer product satisfaction. Accordingly, an aspect of the present invention provides a map matching method in an intersection and navigation system which can provide natural turning guidance at an intersection.

Also, an aspect of the present invention also provides a map matching method in an intersection and navigation system which can provide realistic turning guidance at an intersection, and thereby can help a user drive safely.

Technical solutions

According to an aspect of the present invention, there is provided a method of map matching in an intersection including searching for a route to a destination set by a user and applying a predetermined curvilinear rate to a map matching data used for turning guidance, when an intersection is sensed while driving along the retrieved route.

According to another aspect of the present invention, there is also provided a navigation system including an intersection database to store a curvilinear rate predetermined according to an intersection type and a turn direction, and a control unit to apply, when an intersection is sensed while driving along a route to a destination set by a user, a curvilinear rate corresponding to a type of the sensed intersection and turn direction to a map matching data used for turning guidance at the intersection.

Advantageous Effects

A map matching method in an intersection and a navigation system according to the present invention may apply a predetermined curvilinear rate to map data used for turning guidance in the intersection, and thereby can provide natural and realistic intersection guidance.

Moreover, a turn direction in the intersection is naturally expressed on a map, and thereby enabling a user to drive safely and improving customer product satisfaction.

Brief Description of Drawings

FIG. 1 illustrates a real driving route of a vehicle in an intersection and a corresponding map matching data of an existing navigation terminal;

FIG. 2 illustrates a configuration of a navigation system according to the present invention; FIGS. 3 and 4 illustrate a method for obtaining a coordinate value of a prospective route according to a turn direction when determining a curvilinear rate with respect to a left turn;

FIG. 5 illustrates a method for obtaining a coordinate value of a prospective route according to a turn direction when determining a curvilinear rate with respect to a right turn;

FIG. 6 is a flowchart illustrating a map matching method in an intersection according to the present invention;

FIG. 7 illustrates a map matching data used for turning guidance in an intersection according to the present invention using an exemplary model of a central line of a road with respect to an intersection embodied as a single line; and

FIG. 8 illustrates a map matching data used for turning guidance in an intersection according to the present invention using an exemplary model of a central line of a road with respect to an intersection embodied as a double line.

Best Mode for Carrying Out the Invention

Although a few exemplary embodiments of the present invention have been shown and described, the present invention is not limited to the described exemplary embodiments, wherein like reference numerals refer to the like elements throughout.

First, a configuration of a navigation system used for intersection guidance according to the present invention will be described.

FIG. 2 illustrates a configuration of a navigation system according to the present invention.

The present invention relates to a navigation system including a Global Positioning System (GPS) module 210 that receives a location signal from at least three GPS satellites, and calculates a location of the navigation system itself.

The navigation system of the present invention is a user terminal that provides guidance about a driving route to a destination set by a user. Particularly, while driving along a route, the navigation system can express map matching data in a turning guidance section in a curve.

The navigation system includes a route calculating unit 220, storing unit 230, user interface unit 240, display unit 250, voice output unit 260, and control unit 270. The storing unit 230 includes a map database where map data with respect to a national map and route guidance data related to the map data are set. The storing unit 230 stores a control program to control all operations in the navigation system including a route guidance function and turning guidance function with respect to an intersection while provides guidance about the route. In the turning guidance with respect to the intersection, a curvilinear rate predetermined based on an intersection type and turn direction is applied to map matching data with respect to the turn direction. To achieve the above, previously determining a curvilinear rate with respect to map matching data for each intersection type and turn direction is required. It is desirable that the intersection database is set by separating intersections of a national map according to a type of traffic lane and a form of an intersection and also classifying, for each intersection, a turn direction where driving is possible, and then determining a curvilinear rate for each intersection type and turn direction.

The classifying according to the type of traffic lane classifies the intersections according to a number of traffic lanes, for example a number of one way traffic lanes, and the classifying according to the form of the intersection classifies the intersections into highway, a ring-shape intersection, a right angle-shape intersection, and an X-shape intersection.

Each intersection stored in the intersection database includes code information representing a type of each intersection, and in this instance, the code information includes a code for a type of a traffic lane and a code for a form of an intersection. The turn direction of the intersection that is a driving course where driving is legally permitted for each intersection, includes a right turn, left turn, U-shape turn, P- shape turn, rotary turn, and the like.

The intersection database is to store the intersections included in the national map, the intersection type determined for each intersection, the possible turn direction for each intersection, and the curvilinear rate being predetermined for each turn direction with respect to each intersection type, the intersection database being included in the storing unit 230.

The determining of the curvilinear rate for each intersection type and turn direction is as follows. FIGS. 3 and 4 illustrate a method for obtaining a coordinate value of a prospective route based on a turn direction when determining a curvilinear rate with respect to a left turn, and FIG. 5 illustrates a method for obtaining a coordinate value of a prospective route based on a turn direction when determining a curvilinear rate with respect to a right turn. FIGS. 3 and 5 illustrate a one way one-lane road of a right angle-shape intersection and FIGS. 4 illustrates a one way two-lane road of right angle-shape intersection.

To determine the curvilinear rate for each intersection type and turn direction, a curve equation as shown in Equation 1 can be used. [Equation 1] y = ax^A2 + bx + c

(a, b, c : unknown), To evaluate values of the three unknowns a, b, and c, at least three coordinate values (herein after, base point) ((xl, y2), (x2, y2), (x3, y3), , (xn, yn)) are required.

To determine a curvilinear rate with respect to a left direction in the intersection of FIG. 3, at least three base points are extracted through a prospective route when driving in left direction in the intersection.

For example, since a width of a road corresponding to a single lane is regarded as 3.5 m, when left turning is performed from a one way one-lane road to another road, base points, (3.5/2, -3.5), (0, 0), (-3.5, 3.5/2), are obtained in a turning route.

When substituting the base points respectively into the Equation 1, three equations,

-3.5 = 3.0625a + 1.75b + c with respect to (3.5/2, -3.5),

0 = c with respect to (0, 0), and

1.75 = 12.25a - 3.5b + c with respect to (-3.5, 3.5/2) are obtained. The values of the unknowns, a, b, and c are evaluated by solving simultaneous equations.

In this instance, the values, a = 0.286, b = -2.456, and c = 0, are obtained.

Accordingly, a curve equation with respect to a left turn (a turn direction) in an right angle-shape intersection (a form of an intersection) comprised of a one way one- lane road is y = 0.286x^Λ2-2.456x. That is, the curve equation is determined as a curvilinear rate with respect to the left turn in the one way one-lane right angle-shape intersection.

Also, to determine a curvilinear rate with respect to a left turn in the intersection of FIG. 4, at least three base points are obtained through a prospective route when driving in left direction in the intersection, in the same manner.

In this instance, since the intersection is comprised of a one way two-lane road and a width of the road is regarded as 7 m, when left turning is performed from one-lane of the two-lane road to one-lane of another road, base points, for example, (3.5/2, -7), (0, -3.5), (-3.5, 0), and (-7, 3.5/2) may be obtained in a turning route.

Also, to determine a curvilinear rate with respect to the right turn in the intersection of FIG. 5, at least three base points are obtained through a prospective route when driving in a right direction in the intersection. In this instance, since a width of a road corresponding to a single lane is regarded as 3.5 m, when right turning is performed from a one way one-lane road to another road, base points, (3.5/2, -5), ((3.5/2)+l, 3.5), (3.5, (-3.5/2)-l), and (5, -3.5/2) are obtained in a turning route. A curve equation, namely curvilinear rate, is respectively determined satisfying each condition of FIGS. 4 and 5 through Equation 1 using at least three base points obtained under the same condition illustrated in FIGS. 4 and 5. A curve equation satisfying other condition which is not illustrated may also be determined in the same manner by evaluating unknowns in Equation 1. Accordingly, a curve equation corresponding to an intersection type and turn direction is determined and the curve equation is stored in an intersection database according to an intersection type and turn direction.

Moreover, since a navigation terminal can express a central line of a road as a single line and also a dual line, the navigation terminal can discriminate between the single line and the dual line to determine a curvilinear rate for each intersection type and turn direction.

That is, the curvilinear rate is differently determined depending on a turn direction, whether a model is a single line model or dual line model, a type of lane, and a form of intersection. Also, the navigation terminal can express map matching data with respect to turning guidance in a curve according to a curvilinear rate corresponding to an object intersection type and turn direction when guiding an intersection according to the present invention.

The route calculating unit 220 calculates a current location of a user using a GPS signal received from the GPS module 210 and searches for map data stored in a map database of the storing unit 230 for a route from the current location to a destination set by the user.

The control unit 270 performs route guidance based on route information generated in the route calculating unit 220 while driving along the route. Also, when being close to an intersection in driving along the route, the control unit 270 provides intersection guidance by applying a curvilinear rate corresponding to an intersection type of the close intersection and a turn direction based on the information stored in the intersection database of the storing unit 230.

Also, the display unit 250 is to display every kind of display content according to operations in the whole system and to display map information for providing guidance about the route, which can use a Liquid Crystal Display (LCD), Electro Luminescence (EL), and the like.

The user interface unit 240 is to input user command with respect to a navigation system, such as inputting a destination of a route guidance function and the like. Also, the user interface unit 240 is comprised of a touch pad integrated with the display unit 250, and thereby can provide a graphical user interface. Every menu environment related to the route guidance function of the navigation system is displayed on a graphic screen through the display unit 250 and a user can input a command by touching a specific location on the graphic screen with a stylus pen, finger, and the like.

The voice output unit 260 is to perform voice guidance when providing guidance about a route, which provides the voice guidance based on a turn direction when providing guidance about a turning guidance in an intersection.

A method of map matching in an intersection according to the present invention will be described in detail referring to FIG. 6.

As illustrated, when a user sets a destination of the route guidance function, a route to the set destination is searched for based on a current location.

Subsequently, a map corresponding to the retrieved route is provided and a map matching data with respect to the current location of the user is generated and displayed on the map in operation S610. Then, to enable the user to drive along the route, a map screen with respect to the route and voice guidance is embodied and route guidance is provided.

An intersection located ahead in a driving direction is regularly searched while guiding the route to the destination in operation S620. The searching of the intersection is performed by checking whether a coordinate value of the intersection exists, namely an intersection point, at a predetermined distance ahead of the current location, referring to a map data stored in a map database.

When the intersection is determined while driving along the route, a turn direction in the intersection is verified in operation S630. When the turn direction in the intersection is not a straight direction, but is at least one of a left turn, right turn, U-shape turn, P-shape turn, and rotary turn, the turn direction in the determined intersection and a type of the determined intersection are verified.

Subsequently, a navigation system reads a curve equation corresponding to the verified intersection type and the turn direction from the intersection database of the storing unit 230 and applies a predetermined curvilinear rate to the map matching data with respect to the turn direction of the intersection using the read curve equation in operation S640.

The navigation system outputs, to the map, the map matching data where the curvilinear rate is applied and performs guidance in operation S650.

FIGS. 7 and 8 illustrate an example of a map matching data (M) where a curvilinear rate is applied, and in particular, FIG. 7 shows a model of a central line (L) of a road embodied as a single line and FIG. 8 shows a model of the central line of the road (L) embodied as a double line.

When turning guidance in an intersection is provided, and in particular, when turning guidance to turn left or right is provided, a curvilinear rate corresponding to a type of the corresponding intersection and turn direction is applied to map matching data (M). As illustrated, the map matching data with respect to the turn direction in the intersection is expressed in a curve determined by a curve equation corresponding to the intersection type and turn direction.

Accordingly, since a prospective turning route is different depending on a turn direction, whether a model is a single line or dual line, a type of lane, and a form of intersection and a position of base points obtained from the prospective turning route varies, the turning guidance in an intersection according to the present invention expresses map matching data with a curvilinear rate different for each condition.

A method for map matching in an intersection according to exemplary embodiments of the present invention may be recorded in computer-readable media including program instructions to implement various operations embodied by a computer. The media may also include, alone or in combination with the program instructions, data files, data structures, and the like. Examples of computer-readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD ROM disks and DVD; magneto-optical media such as optical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like. The media may also be a transmission medium such as optical or metallic lines, wave guides, and the like, including a carrier wave transmitting signals specifying the program instructions, data structures, and the like. Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. The described hardware devices may be configured to act as one or more software modules in order to perform the operations of the above-described exemplary embodiments of the present invention.

Although a few embodiments of the present invention have been shown and described, the present invention is not limited to the described embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method of map matching in an intersection, comprising: searching for a route to a destination set by a user; and applying a predetermined curvilinear rate to map matching data used for turning guidance, when an intersection is determined while driving along the retrieved route.

2. The method of claim 1, further comprising: maintaining an intersection database where the predetermined curvilinear rate is stored, the predetermined curvilinear rate being predetermined according to an intersection type and a turn direction.

3. The method of claim 2, wherein the applying comprises: verifying a type of the determined intersection and turn direction when the intersection is sensed while driving along the retrieved route; applying a curvilinear rate corresponding to the verified type of the intersection and turn direction to the map matching data used for the turning guidance.

4. The method of claim 2, wherein the maintaining comprises: classifying intersections of a national map according to a type of a traffic lane and a form of an intersection, and determining intersection types; determining, for each intersection, a turn direction where driving is possible; determining a curvilinear rate for each turn direction with respect to each of the determined intersection types.

5. The method of claim 4, wherein the classifying according to the type of the traffic lane classifies the intersections according to a number of the traffic lanes.

6. The method of claim 4, wherein the classifying according to the form of the intersection classifies the intersections into an interchange, a rotary intersection, a right angle-shape intersection, and an X-shape intersection.

7. The method of claim 4, wherein the turn direction comprises a right turn, left turn, U-shape turn, P-shape turn, and rotary turn.

8. The method of claim 4, wherein the determining of the curvilinear rate for each turn direction with respect to each of the determined intersection types comprises: obtaining at least three coordinate values through a prospective route according to each turn direction of a corresponding intersection; applying the at least three coordinate values to Equation 1 and determining a curvilinear equation with respect to an intersection type and turn direction of the corresponding intersection. [Equation 1] y = ax^Λ2 + bx + c (a, b, c : unknown)

9. The method of claim 8, wherein the applying of the curvilinear rate corresponding to the verified type of the intersection and turn direction to the map matching data used for the turning guidance comprises: reading a curvilinear equation corresponding to the verified type of the intersection and turn direction from the intersection database; generating map matching data according to a curve based on the read curvilinear equation; and outputting the generated map matching data on a map to perform turning guidance at the intersection.

10. A computer-readable storage medium recording a program for implementing the method according to any one of claims 1 to 9.

11. A navigation system, comprising: an intersection database to store a curvilinear rate predetermined according to an intersection type and a turn direction; and a control unit to apply, when an intersection is sensed while driving along a route to a destination set by a user, a curvilinear rate corresponding to a type of the sensed intersection and turn direction to a map matching data used for turning guidance at the intersection.