JP2806149B2 - Navigation device with route calculation function - Google Patents

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 two designated points.

[0002]

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

[0003] Navigation devices having a route calculation function have also been put to practical use. In an apparatus having a route calculation function, generally, when a destination is set, road map data including a calculation start link to a calculation end link is stored in a road map memory using the current vehicle position as a calculation start link and a destination as a calculation end link. And the optimum route within the range of the road map data is automatically calculated and displayed on the display. The vehicle driver will follow the optimal route shown,
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 transferred to the work area.
The route is calculated in the work area based on the Dijkstra method or the like. By the way, when highways are 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 the data cannot be stored in the work area at one time. is there.

[0005] It is conceivable to use a method in which a driver sets a waypoint and performs a division calculation. However, the calculation from the departure point to the destination requires human judgment, and the optimum route is calculated automatically. This does not fit the purpose of the navigation device. Therefore, there is a need for a navigation device that can calculate an optimal route in a short time without increasing the capacity of a work area.

[0006]

According to the first aspect of the present invention,
A navigation device having a route calculation function for calculating an optimum route when traveling between two designated points, wherein one of two links close to a departure point and a set destination is calculated, and the other is a calculation start link. Is used 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 work area capacity, the area including the calculation start link and the intermediate point An intermediate point such that the data amount of the road map data corresponding to does not exceed the capacity of the work area is specified, and based on the road map data corresponding to the intermediate area including the calculation start link and the specified intermediate point, Starting from the calculation start link, the link cost of the route to each link existing at the end of the intermediate area is determined, and the link cost existing at the end of the intermediate area is determined. One link selected by a predetermined standard is determined among the links to be calculated, a route from the calculation start link to this link is set as an intermediate route, this link is set as a new calculation start link, and this new calculation start link is set. A road map corresponding to an area including the new calculation start link and the calculation end link obtained as described above by repeating the above-described processing as necessary for the calculation end link and the calculation end link. If the data is not expected to exceed the memory capacity of the work area, the final route from the calculation start link to the calculation end link is calculated based on the road map data corresponding to this area, and the calculated value is calculated as described above. The optimum route is obtained by connecting the obtained intermediate route and the final route.

[0007]

According to the first aspect of the present invention, 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 used. Based on the road map data corresponding to the intermediate area including the above, 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, one of the links existing at this end is selected by a predetermined standard as a new calculation start link, and the above-described processing is repeated to obtain a route. By connecting these routes, The optimum 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 below in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a navigation device according to one embodiment of the present invention. This navigation device is mounted on a vehicle and used to support traveling in the vehicle. This device includes, as sensors, a geomagnetic sensor 1 for detecting an azimuth, a vehicle speed sensor 2 for detecting a speed of a vehicle,
Further, 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 determined by the navigation ECU.
4 to a locator 5. Further, a vibration gyro sensor 6 for detecting a turning angle of the vehicle is provided in the navigation ECU 4, and a detection output of the vibration gyro sensor 6 is also provided to the locator 5.

The locator 5 is for calculating the current position of the vehicle. The locator 5 calculates the azimuth change amount of the vehicle based on the azimuth detected by the geomagnetic sensor 1 and the turning angle of the vehicle detected by the vibration gyro sensor 6. In addition, 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 provided from the shift sensor 3. Therefore, for example, if the vehicle's accurate initial position data is given to the locator 5 before the vehicle starts moving,
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 stored in an MIC (Multi Information
Controller) 7. The MIC 7 is a control center of the navigation ECU 4, and has a CPU, a ROM, an R
AM etc. are included. MIC7 is the navigation ECU
Locator 5 and CD drive 8 provided in 4
And to a graphic generator 10 provided outside the navigation ECU 4. A monitor control unit 11 is connected to the graphic generator 10.
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 has a CD drive 8 and a CD drive 8 based on the current position data of the vehicle calculated by the locator 5 and the like.
It controls the autochanger 15. CD drive 8
In response to a control signal given from the MIC 7, display road map data corresponding to the current position of the vehicle is read from the previously loaded dedicated map disk D 1 and output to the MIC 7. The MIC 7 supplies the current position data calculated by the locator 5 and the road map data supplied from the CD drive 8 to the graphic generator 10 to generate a map and a vehicle current position mark on the map. The map and the current location mark of the vehicle generated by the graphic generator 10 are provided to the monitor control unit 11 and displayed on the display unit 12.

The CD autochanger 15 is provided with a
In response to a control signal given from C7, the CPU reads route map data for route calculation from the route calculation disk D2 loaded in advance and outputs the map data to the MIC. By operating the touch switch 13 and the mechanical switch 14 on the monitor control unit 11, the display on the display unit 12 is switched or a predetermined control signal is given to the MIC 7.

The route calculation map data is obtained by dividing a road map (including a highway, a motorway, an exclusive road, a national road, a prefectural road, a city road of a designated city, and other living roads) into meshes. A route composed of a combination of nodes and links in units is separately stored in a map corresponding to an expressway and a map corresponding to an arterial road. Highway-compatible maps are mainly expressways (highway expressways, motorways,
The highway-corresponding map includes highways as well as highways (national roads and prefectural roads). Due to the characteristics of the map database, nationwide closed networks are formed for roads higher than national roads among the main roads.

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

The road map data for position calculation is created from a map database of 1/2500, and is more detailed and precise data than the map data for route calculation.
This is a one-layer data comprising node position information and some link information (road width, etc.). The number of types of link information is small because it does not include required time data or traffic regulation data that is not directly needed for position detection (however, road width may be useful for position detection as well. Is).

As described above, the road map data for position detection and the map data for route calculation are separated. The former requires detailed accuracy for map matching, and the latter requires more accurate route calculation than accuracy. This is because it is necessary to attach various data. The display road map data is 25
Roads, created from a 1:00 map database
It is composed of map data and the like for specifying place names, famous facilities, railways, rivers, and the like.

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, a potential method, which is a kind of the Dijkstra method), to move from the current position to the destination. Of the optimal route of This potential method is
Start calculation of the link closest to the destination (departure point) Link O
The link closest to the departure point (destination) is defined as the calculation end link M _O , and the calculation start link O to the calculation end link M
_This is a method in which a link tree is constructed by sequentially adding the link costs reaching _O, and only the route with the lowest link cost that reaches the calculation end link MO is selected. Here, items to be considered when estimating the link cost include mileage, travel time, use of highway, right / left turn count, highway running probability, avoidance of accident-prone areas, and other settings according to the driver's preference. There is a matter. As a work area for executing this potential method, the MIC 7 of the navigation ECU 4 prepares a buffer area of 512 kbytes on the RAM.

A beacon unit 16 may be 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 road side of a road or the like. The beacon data received by the beacon receiver 17 is provided to the MIC 7 via the beacon unit 16 and is finally displayed on the display unit 12 to display the beacon information to the driver. As an optional device, the locator 5 has a GPS
A GPS receiver 19 may be connected via the unit 18. When the GPS unit 18 and the GPS receiver 19 are provided, it is possible to receive a signal from a GPS satellite and accurately detect the absolute azimuth, or directly detect the current position of the moving object.

FIG. 2 shows the display unit 12 and the mechanical switch 14.
It is an external appearance front view which shows a specific example of the display which has a etc. This indicator is integrated in a motor vehicle, for example, in a front console box. The display unit has a display unit 12 disposed on a main surface of the display unit, and displays various data including a map, a current vehicle position, and an optimum route, as described later. Further, a transparent electrode panel is disposed on the surface of the display unit 12, and when the switch contents, that is, the position to be pressed and the switch type are displayed on the display unit 12, the switch can be operated. A so-called touch switch 13 is provided.

On both sides of the display section 12, several mechanical switches 14 are provided. 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, Return switch 14d for returning to
A cursor key 14e for moving a displayed cursor and scrolling a display screen, and a set switch 14f for setting data are provided.

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

When it is determined that there is a request for route calculation, MI
C7 operates the CD drive 8, reads the route calculation program from the route calculation disk D2 loaded in the CD autochanger 15, and transfers the calculation program to the MIC7.
Is loaded into, for example, an SRAM (step S3). Then, the current position detected by the locator 87 as calculation start link O, as the calculation end link M _O a destination set, route calculation is performed (step S4).

The obtained optimum route is displayed on the display unit 12.
Is displayed (step S5). Hereinafter, the procedure of the route calculation will be described in detail. First, assuming that the distance between the calculation start link S and the calculation end link M _O is D, a rectangular area of the road map including the calculation start link S and the calculation end link M _O is specified. 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 a graph (FIGS. 5 and 6) showing the relationship between these parameters V and H and the distance D.
Identify a rectangular area.

[0024] Incidentally, to choose a rectangular region, experience of the length of the calculated optimum route, as compared with the computational start links S and the straight line distance between the calculation end link M _O, does not become extremely long It is based on rules. 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. If less, that is, when possible route calculation map data acquisition is performed the read route calculation map data of the mesh included in the rectangular area, the calculation of the optimal path by potential method to the calculation end links M _O .

In many cases, a half point of 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 graphed (FIG. 5, FIG. 5).
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 targets. A similar determination is made. Thus, the intermediate points M ₃ , M
₄ Repeat the determination of ...
The intermediate region R _3, R _4, data capacity of meshes included in ... is, to determine the midpoint M _{i + 1} greater than the data capacity of the work area, an intermediate in the midpoint M _i one before that Region R
_Get 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 /
2 points as the midpoint M _2, a determination is similar to the calculation-start link S and the middle point M ₂ as a target. In this way, the route calculation map data of the intermediate area R _i at the intermediate point Mi _immediately before the data capacity of the work area is obtained.

The route is calculated based on the acquired route calculation map data. 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 a plurality of such end links usually exist as shown in FIGS. 9A, 9B, and 9C, one link must be determined according to a certain standard. This criterion is, for example, the road type is prioritized end link is national road, the straight line distance between the calculation end link M _O to give priority to the nearest end link, or the link costs to the end link,
The sum of the linear cost of calculation end link M _O is preferentially the smallest end link is. Either or both of these criteria may be employed. When both are adopted, weighting is performed for evaluation, but in the case of the embodiment, as described above, a nationally closed network is formed for national roads due to the characteristics of the map database as described above. , With emphasis on evaluation.

When the end link is determined according to this criterion, an intermediate path from the calculation start link S to the end link is obtained, and the end link is set as the calculation start link S, and the calculation end link M
The intermediate route to _O is obtained by following the same procedure as above. The route connecting the intermediate routes is the optimal route.
FIG. 10 shows a series of intermediate areas and the optimum route determined as described above.

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

[0032]

According to the first aspect of the present invention, even when the data amount of the road map data including the calculation start link and the calculation end link exceeds the capacity of the work area, the intermediate area is automatically determined. Then, an intermediate route to a predetermined link at the end of the intermediate region is calculated, and these intermediate routes are connected to obtain an optimal route to the calculation end link. 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 a line connecting the calculation start link and the intermediate point is substantially the long side direction, the path calculation is performed in this area. Then, compared with the case where the route calculation is performed in the square area, the route of the large round trip 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 having a direction of a line connecting the calculation start link and the intermediate point as a direction of a major axis, the path calculation is performed in this area. Then, compared to the case where the route calculation is performed in a square area, there is no possibility that a large-scale 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 a link having the shortest linear distance from the calculation end link among the links existing at the end of the intermediate area.
The optimum route can be calculated efficiently. According to the fifth aspect of the present invention, 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 linear distance between each existing link and the calculation end link. The optimum route can be calculated efficiently.

According to the sixth aspect of the present invention, since a road having a higher road type can be selected from the links existing at the end of the intermediate area, it is preferable to give priority to traveling on a higher road. . In the invention described in claim 7, the intermediate point is on a line connecting the calculation start link and the calculation end link, so that it is possible to easily determine the intermediate point.

[Brief description of the drawings]

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

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

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

FIG. 4 is a diagram illustrating 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 of determining an intermediate point.

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

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

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

[Explanation of symbols]

 4 Navigation ECU 5 Locator 7 MIC 8 CD Drive 14 Mechanical Switch 15 CD Autochanger D2 Route Calculation Disk

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01C 21/00 G06F 17/00 G08G 1/0969 G08G 1/123

Claims (7)

(57) [Claims] 1. Road map storage means for storing road map data, input means for inputting a route calculation request signal, and storage in the road map storage means in response to input of a route calculation request signal from the input means. Loading means for reading out the road map data thus set and moving it to the work area, and an optimum means for traveling between two links which are respectively close to the departure point and the set destination based on the road map data transferred to the work area. A navigation device having a route calculation function, comprising: a route calculation unit that calculates a route, wherein the route calculation unit calculates one of two links close to the departure point and the 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,
If the memory capacity is expected to exceed the capacity of the route calculation work area, specify an intermediate point such that the data amount of the 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. And based on road map data corresponding to an intermediate region including the calculation start link and the specified intermediate point, a link of a route from the calculation start link to each link existing at an end of the intermediate region, starting from the calculation start link. The cost is determined, one of the links existing at the end of the intermediate area is determined based on a predetermined criterion, and the path from the calculation start link to this link is set as the intermediate path. As a new calculation start link, the above process is repeated as necessary for the new calculation start link and the calculation end link to obtain an intermediate route, and the If 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 manner does not exceed the memory capacity of the work area, the road map data corresponding to this area is used. Calculating the final route from the calculation start link to the calculation end link, and obtaining the optimum route by connecting the intermediate route and the final route obtained as described above. Navigation device with functions. 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 connecting the calculation start link and the intermediate point is substantially a long side. 3. The navigation device having a route calculation function according to claim 1, wherein the intermediate area is an ellipse having a direction of a line connecting the calculation start link and the intermediate point substantially as a long axis direction. 4. A 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-line distance from a calculation end link. 5. A predetermined criterion for determining one of the links existing at the end of the intermediate area is a link cost from a calculation start link to each link existing at the end, and existing links and calculation end links. The navigation device having a route calculation function according to claim 1, wherein the navigation device has a straight-line distance from the navigation device. 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. A navigation device having a route calculation function according to claim 1, wherein said intermediate point is on a line segment connecting a calculation start link and a calculation end link.