JPH05340762A - Navigation device with route calculating function - Google Patents

Abstract

PURPOSE:To find the optimum route to a calculation terminating link by deciding intermediate areas and calculating intermediate routes to prescribed links at the ends of the intermediate areas, and connecting the intermediate routes. CONSTITUTION:An MIC (multi-information controller) 7 actuates a CD driver 8 when the MIC 7 discriminates that a route calculating request is made and loads a route calculating program by reaing out the proqram from a route calculation disk D2. Then the MIC 7 carries out route calculation by using the current location detected by means of a locator 5 as a calculation starting link S and a set destination as a calculation terminating link M and displays the obtained final route on the displaying section 12. Thereafter, the MIC retrieves the management area of the disk D2 and obtains map data for calculating route by specifying an intermediate area aqainst the link S and an intermediate point M1 by using the middle point between the links S and M0 as the intermediate point M1 when the data capacity of meshes contained in the management area is large. The MIC calculates the route based on the map data and finds the optimum route by connecting intermediate points.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation device having a function of calculating an optimum route when traveling between designated two points.

[0002]

2. Description of the Related Art Various navigation devices have been realized which are mounted on a vehicle to display the current location of the vehicle so as to assist the traveling of the vehicle. The conventional navigation device detects the current position of the vehicle based on the outputs from, for example, the direction sensor and the vehicle speed sensor. On the other hand, a road map including the detected current location is read out from a map memory composed of a CD-ROM or the like and electronically displayed. Then, the detected vehicle current position is overlaid and displayed on the displayed road map.

A navigation device having a route calculation function has also been put into practical use. In a device equipped with a route calculation function, generally, when a destination is set, the vehicle current position is used as a calculation start link, the destination is used as a calculation end link, and road map data including the calculation start link to the calculation end link is stored in the road map memory. The optimum route is automatically calculated within the range of this road map data and displayed on the display. The vehicle driver can
You can drive safely without getting lost.

[0004]

In order to execute the route calculation in the navigation device, the road map data stored in the road map memory is read out and moved to the work area.
The route is calculated in the work area based on the Dijkstra method or the like. By the way, if the expressway is not used in a densely populated area such as an urban area, the amount of road map data from the calculation start link to the calculation end link becomes enormous and it cannot be stored in the work area at one time. is there.

A method of setting a waypoint to a driver and performing division calculation is also conceivable, but it requires a human judgment to calculate from the departure point to the destination, and the optimum route is automatically calculated. It does not serve the purpose of the navigation device. Therefore, there is a demand for a navigation device that can calculate an optimum route in a short time without increasing the capacity of the work area.

[0006]

The invention according to claim 1 is
A navigation device having a route calculation function for calculating an optimum route when traveling between designated two points, wherein one of two links near a departure place and a set destination is a calculation start link, and the other is a calculation start link. As the calculation end link, the data amount of the road map data including the calculation start link and the calculation end link is estimated, and when the memory capacity is expected to exceed the capacity of the work area, the area including the calculation start link and the intermediate point. The midpoint such that the data amount of the road map data equivalent to does not exceed the capacity of the work area is specified, and based on the road map data corresponding to the midpoint area including the calculation start link and the specified midpoint, For the first time from the calculation start link, the link cost of the route to each link existing at the end of the intermediate area is obtained, and the link cost exists at the end of the intermediate area. One link selected based on a predetermined standard among the respective links is determined, the route from the calculation start link to this link is set as an intermediate route, and this link is set as a new calculation start link. The road map corresponding to the area including the new calculation start link and the new calculation end link, which are obtained as described above, by repeating the above processing for the calculation end link and the calculation end link to obtain the intermediate route. When it is expected that the data will not exceed the memory capacity of the work area, calculate the final route from the calculation start link to the calculation end link based on the road map data corresponding to this area, and calculate as described above. The optimum route is obtained by connecting the obtained intermediate route and final route.

[0007]

According to the invention described in claim 1, when the data amount of the road map data including the calculation start link and the calculation end link is expected to exceed the capacity of the work area, the calculation start link and the intermediate point having a small data amount are provided. Based on the road map data corresponding to the intermediate area including, the link cost of the route from the calculation start link to each link existing at the end of the intermediate area is calculated. Then, among the links existing at this end, one link selected by a predetermined standard is used as a new calculation start link, the above process is repeated to obtain a route, and by connecting these routes, The optimal route to the calculation end link can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a navigation device according to an embodiment of the present invention. This navigation device is installed in a vehicle and is used for supporting traveling in the vehicle. In this device, as sensors, a geomagnetic sensor 1 for detecting a direction, a vehicle speed sensor 2 for detecting the speed of a vehicle,
Also, a shift sensor 3 for detecting whether the vehicle is moving forward or backward is provided. The detection outputs of these three sensors 1, 2, 3 are navigation ECUs.
Given to locator 5 in 4. A vibration gyro sensor 6 for detecting the turning angle of the vehicle is provided in the navigation ECU 4, and the detection output of the vibration gyro sensor 6 is also given to the locator 5.

The locator 5 is for calculating the current position of the vehicle, and based on the direction detected by the geomagnetic sensor 1 and the turning angle of the vehicle detected by the vibration gyro sensor 6, the directional change amount of the vehicle is calculated. Further, the vehicle speed detected by the vehicle speed sensor 2 is integrated, and the moving distance of the vehicle is calculated in consideration of the forward or backward movement of the vehicle given from the shift sensor 3. Therefore, for example, if accurate initial position data of the vehicle is given to the locator 5 before the vehicle starts,
The locator 5 calculates the current position of the vehicle thereafter.

Data representing the current position of the vehicle calculated by the locator 5 is MIC (Multi Information) in the ECU 4.
Controller) 7 is given. The MIC 7 is a control center of the navigation ECU 4, and includes a CPU, a ROM, and an R.
Includes AM etc. MIC7 is a navigation ECU
Locator 5 and CD drive 8 provided in
And the graphic generator 10 provided outside the navigation ECU 4. A monitor controller 11 is connected to the graphic generator 10, and a CR is connected to the monitor controller 11.
A display unit 12 such as T, a plurality of touch switches 13, and a plurality of mechanical switches 14 are provided.

The MIC 7 is a CD drive 8 and a CD based on the current position data of the vehicle calculated by the locator 5.
Control the autochanger 15. CD drive 8
In response to the control signal given from the MIC 7, the road map data for display corresponding to the current vehicle location is read from the map-dedicated disk D1 loaded in advance and output to the MIC 7. The MIC 7 supplies the current location data calculated by the locator 5 and the road map data provided from the CD drive 8 to the graphic generator 10 to generate a map and a vehicle current location mark on the map. The map and the current position mark of the vehicle generated by the graphic generator 10 are given to the monitor control unit 11 and displayed on the display unit 12.

Further, the CD autochanger 15 is an MI
In response to the control signal given from C7, the route calculation map data for route calculation is read from the route calculation disk D2 loaded in advance, and is output to the MIC7. By operating the touch switch 13 and the mechanical switch 14 on the monitor control unit 11, the display of the display unit 12 is switched or a predetermined control signal is given to the MIC 7.

The map data for route calculation is obtained by dividing a road map (including highway national roads, motorways, national roads, prefectural roads, city roads of designated cities, and other living roads) into meshes, and each mesh is divided. A route consisting of a combination of a node and a link is divided into a highway correspondence map and a highway correspondence map and stored. Maps for highways are mainly highways (highway national roads, motorways,
The main road correspondence map includes main roads (national roads, prefectural roads) as well as highways. Due to the characteristics of the map database, a closed network is formed nationwide for highways and higher roads among the main roads.

Here, a node is generally a coordinate point for specifying a road intersection, a mesh boundary, a dead end, etc., and a node representing an intersection may be called an intersection node. A link connects each node. The link data is the link number, the address of the start and end nodes of the link, the distance of the link, the direction of passing the link, the required time data in that direction, the road type, the road width, one-way, right turn prohibited, left turn prohibited and toll road Including traffic regulation data such as.

The position calculation road map data is created from a map database of 1/2500 and is more detailed and precise than the route calculation map data.
This is one-layer structure data consisting of node position information and some link information (road width, etc.). The type of link information is small because it does not include required time data and traffic regulation data that are not directly required for position detection (however, the road width may be useful for position detection, so it is included). Have been).

In this way, the road map data for position detection and the map data for route calculation are separated. The former requires detailed precision for map matching, and the latter requires route calculation rather than precision. This is because it is necessary to attach various data. In addition, the road map data for display is 25
Roads created from the 1/00 map database,
It is made up of map data, etc. that specify place names, famous facilities, railways, rivers, etc.

Based on the route calculation map data read from the route calculation disk D2, the MIC 7 uses the Dijkstra method or the like (in the embodiment, the potential method which is a kind of Dijkstra method is adopted) from the present location to the destination. Calculates the optimal route of. This potential method
Start the link closest to the destination (departure) Link O
, The link closest to the starting point (destination) is the calculation end link M _O , and the calculation start link O to the calculation end link M
_This is a method in which the link costs reaching _O are sequentially added to form a tree of links, and only the route having the lowest link cost reaching the calculation end link M _O is selected. Items to be considered when estimating the link cost include mileage, travel time, availability of highways, number of right and left turns, highway driving probability, avoidance of accident-prone areas, and other settings according to driver preference. There are matters I have done. As a work area for executing this potential method, the MIC 7 of the navigation ECU 4 prepares a 512 kbyte buffer area on the RAM.

A beacon unit 16 may be further connected to the MIC 7, and a beacon receiver 17 may be connected to the beacon unit 16. Beacon receiver 17
Is for receiving data such as position information and road information (intersection name, destination guidance) radiated from a beacon antenna installed on the roadside of the road. The beacon data received by the beacon receiver 17 is given to the MIC 7 via the beacon unit 16 and finally displayed on the display unit 12 to display the beacon information to the driver. In addition, as an optional device, GPS can be attached to the locator
The GPS receiver 19 may be connected via the unit 18. When the GPS unit 18 and the GPS receiver 19 are provided, signals from GPS satellites can be received to accurately detect the absolute azimuth or directly detect the current position of the mobile body.

FIG. 2 shows the display section 12 and the mechanical switch 14.
FIG. 14 is an external front view showing a specific example of a display unit having the above. This indicator is incorporated in, for example, a front console box of a vehicle. The display unit has a display unit 12 arranged on the main part of its surface, and displays various data such as a map, a current vehicle position, and an optimum route, as will be described later. In addition, a transparent electrode panel is arranged on the surface of the display unit 12, and when the display unit 12 displays the switch contents, that is, the position to be pressed and the switch type, the switch can be operated. A so-called touch switch 13 is provided.

Several mechanical switches 14 are provided on both sides of the display section 12. In this embodiment, a navigation switch 14a for displaying a map, an information switch 14b for displaying various kinds of guidance information, a memo switch 14c for performing a memo function described later, and a previous screen of display contents. Return switch 14d for returning to
A cursor key 14e for moving the displayed cursor and scrolling the display screen, and a set switch 14f used for setting data are provided.

FIG. 3 is a flow chart showing a schematic control procedure when the route is calculated in the navigation system of this embodiment. Explaining according to the flow of FIG. 3, after the destination is set (step S1), the MIC 7 determines whether or not a route calculation request is input (step S1).
2). The route calculation request input is, for example, the display unit 1 shown in FIG.
This is done by pressing a touch switch or the like (not shown) displayed on the display 2.

If it is determined that there is a request for route calculation, MI
C7 operates the CD drive 8 to read the route calculation program from the route calculation disk D2 loaded in the CD autochanger 15, and to execute the calculation program on the MIC7.
It is loaded into, for example, SRAM (step S3). Next, route calculation is performed with the current location detected by the locator 5 as the calculation start link O and the set destination as the calculation end link M _O (step S4).

Then, the obtained optimum route is displayed on the display unit 12.
Is displayed (step S5). The procedure of route calculation will be described in detail below. First, the rectangular area of the road map including the calculation start link S and the calculation end link M _O is specified by setting the distance between the calculation start link S and the calculation end link M _O as D. For this purpose, a parameter V related to the length of the short side of the rectangle and a parameter H related to the length of the long side of the rectangle are defined (see FIG. 4). Then, based on the distance D, the parameters V and H are obtained using graphs (FIGS. 5 and 6) showing the relationship between these parameters V and H and the distance D,
Identify the rectangular area.

It should be noted that the rectangular area is selected so that the calculated optimum path length is never extremely longer than the straight line distance between the calculation start link S and the calculation end link M _O. It is based on the law. Therefore, it not necessarily limited to a rectangle, even ellipse centered example the calculation start link S and the calculation end link M _O.

Next, the management area of the route calculation disk D2 is searched to estimate whether the data capacity of the mesh included in the rectangular area is smaller than the data capacity of the work area. When the number is small, that is, when the route calculation map data can be acquired, the route calculation map data of the mesh included in the rectangular area is read out, and the optimal route to the calculation end link M _{O is} calculated by the potential method. ..

In many cases, a half point between the calculation start link S and the calculation end link M _O is set as the intermediate point M ₁ , and the calculation start link S and the intermediate point M ₁ are set as a graph (FIG.
Identify intermediate region R ₁ seeking parameters V, H using 6), determines whether the data volume of the mesh included in the intermediate region R ₁ is less than the data capacity of the work area.

If the number is small, as shown in FIG. 7, a half point between the calculation end link M _O and the intermediate point M ₁ is set as the intermediate point M ₂ , and the calculation start link S and the intermediate point M ₂ are set as the above-mentioned points. The same judgment is made. In this way, the intermediate points M ₃ , M
₄ , ..., and determination of data size are repeated.
The data capacity of the meshes included in the intermediate areas R ₃ , R ₄ , ... Determines the intermediate point M _{i + 1} which exceeds the data capacity of the work area, and determines the intermediate point at the intermediate point M _i one before that. Region R
_Obtain map data for route calculation of _i .

Further, the data capacity of the mesh included in the intermediate region R ₁ is The more than data capacity of the work area, the calculation start link S and the middle point M ₁ as shown in FIG. 8 1 /
The second point is set as the intermediate point M ₂ and the same determination as the above is performed for the calculation start link S and the intermediate point M ₂ . In this way, the route calculation map data of the intermediate area R _{i at} the immediately preceding intermediate point M _{i that} is less than the data capacity of the work area is acquired.

Then, a route is calculated based on the acquired map data for route calculation. The route calculation is performed from the calculation start link S to the link at the end of the mesh included in the intermediate region R _i . Since there are usually a plurality of such end links as shown in FIGS. 9a, 9b, and 9c, one link must be determined according to a certain standard. The criteria include, for example, giving priority to an end link whose road type is a national road, giving priority to an end link having the shortest linear distance from the calculation end link M _O , or a link cost to the end link,
That is, the end link having the smallest sum of the calculation end link M _O and the linear cost is prioritized. Either or both of these criteria may be adopted. When both are adopted, they are weighted and evaluated, but in the case of the embodiment, as described above, because of the characteristics of the map database, a nationally closed network is formed for national roads. The evaluation is focused on ,.

When the end link is determined according to this criterion, an intermediate route between the calculation start link S and the end link is obtained, and the end link is set as the calculation start link S, and the calculation end link M is calculated.
_Follow the same procedure as above to find the intermediate route to _O. The route connecting the intermediate routes is the optimal route.
FIG. 10 shows a series of intermediate regions and optimum routes determined as described above.

The present invention is not limited to the above embodiment. In the above embodiment, the intermediate point is determined as the half point of the calculation start link and the calculation end link. However, if the intermediate point is on the line segment connecting the calculation start link and the calculation end link, Of course, points other than 1/2 may be adopted.

[0032]

According to the first aspect of the invention, the intermediate area is automatically determined even when the amount of road map data including the calculation start link and the calculation end link exceeds the capacity of the work area. Then, by calculating each intermediate route to a predetermined link at the end of the intermediate region and connecting these intermediate routes, the optimal route to the calculation end link can be obtained. Therefore, the route from the calculation start link to the calculation end link can be automatically and promptly calculated without particularly increasing the capacity of the work area.

According to the second aspect of the present invention, since the intermediate area is a rectangle whose direction of the line segment connecting the calculation start link and the intermediate point is substantially the long side direction, route calculation is performed in this area. By doing so, as compared with the case where the route calculation is performed in the square area, the roundabout route is not calculated, and the optimum route can be calculated more quickly.

According to the third aspect of the present invention, since the intermediate area is an ellipse whose direction of the line segment connecting the calculation start link and the intermediate point is substantially the major axis direction, the route calculation is performed in this area. By doing so, as compared with the case where the route calculation is performed in the square area, there is no possibility that a roundabout route is calculated, and the optimum route can be calculated more quickly.

According to the fourth aspect of the present invention, it is possible to select the link having the shortest linear distance from the calculation end link among the links existing at the end of the intermediate area.
The optimal route can be calculated efficiently. According to the invention of claim 5, it is possible to select the link having the smallest link cost from the calculation start link to each link existing at the end and the smallest linear distance between each existing link and the calculation end link. The optimal route can be calculated efficiently.

According to the sixth aspect of the present invention, it is possible to select a road having a higher road type among the links existing at the end of the intermediate area. Therefore, it is suitable when priority is given to running on a higher road. .. In the invention according to claim 7, since the intermediate point is on the line segment connecting the calculation start link and the calculation end link, it is possible to easily determine the intermediate point.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a navigation device according to an embodiment of the present invention.

FIG. 2 is an external front view showing a specific example of the display device of the navigation device according to the embodiment of the present invention.

FIG. 3 is a flowchart for explaining a route calculation processing procedure in the navigation device according to the embodiment of the present invention.

FIG. 4 is a diagram showing a rectangular area including a calculation start link and a calculation end link.

FIG. 5 is a graph for determining a rectangular parameter V based on a distance D between a calculation start link and a calculation end link.

FIG. 6 is a graph for determining a rectangular parameter H based on a distance D between a calculation start link and a calculation end link.

FIG. 7 is a diagram for explaining a method for determining an intermediate point.

FIG. 8 is a diagram for explaining a method for determining an intermediate point.

FIG. 9 is a diagram showing the existence of end links included in an intermediate area.

FIG. 10 is a diagram showing a determined series of intermediate regions and optimum routes.

[Explanation of symbols]

 4 Navigation ECU 5 Locator 7 MIC 8 CD Drive 14 Mechanical Switch 15 CD Auto Changer D2 Route Calculation Disc

Claims (7)

[Claims] 1. A road map storage means for storing road map data, an input means for inputting a route calculation request signal, and a road map storage means for storing a route calculation request signal from the input means. Optimum for traveling between two links, which are respectively close to the starting point and the set destination, based on the loading means for reading the read road map data and moving it to the work area and the road map data transferred to the work area. In a navigation device having a route calculation function, which includes a route calculation unit for calculating a route, the route calculation unit calculates one of two links close to a departure place and a set destination, respectively,
Using the other as the calculation end link, estimate the data amount of the road map data including the calculation start link and the calculation end link,
When the memory capacity is expected to exceed the capacity of the route calculation work area, an intermediate point is specified so that the amount of road map data corresponding to the area including the calculation start link and the intermediate point does not exceed the capacity of the work area. However, based on the road map data corresponding to the intermediate area including the calculation start link and the specified intermediate point, the link of the route from the calculation start link to each link existing at the end of the intermediate area for the first time. The cost is calculated, one of the links existing at the end of the intermediate area is selected based on a predetermined criterion, and the route from the calculation start link to this link is set as the intermediate route. As a new calculation start link, the above processing is repeated as necessary for the new calculation start link and the calculation end link to obtain an intermediate path, and When it is expected that the road map data corresponding to the area including the new calculation start link and the calculation end link obtained in this way will not exceed the memory capacity of the work area, based on the road map data corresponding to this area , A route calculation characterized in that the final route from the calculation start link to the calculation end link is calculated, and the optimum route is obtained by connecting the intermediate route and the final route obtained as described above. A navigation device having a function. 2. The navigation device having a route calculation function according to claim 1, wherein the intermediate area is a rectangle whose direction of a line segment connecting the calculation start link and the intermediate point is substantially the long side direction. 3. The navigation device having a route calculation function according to claim 1, wherein the intermediate region is an ellipse having a direction of a line segment connecting the calculation start link and the intermediate point as a major axis direction. 4. The navigation device having a route calculation function according to claim 1, wherein the predetermined criterion for determining one of the links existing at the end of the intermediate area is a straight distance from the calculation end link. 5. The predetermined criterion for determining one of the links existing at the end of the intermediate area is the link cost from the calculation start link to each link existing at the end, and the existing links and the calculation end links. A navigation device having a route calculation function according to claim 1, which is a straight line distance from 6. The navigation device having a route calculation function according to claim 1, wherein the predetermined criterion for determining one of the links existing at the end of the intermediate area is a road type of the link. 7. The navigation device having a route calculation function according to claim 1, wherein the intermediate point is on a line segment connecting a calculation start link and a calculation end link.