JPH03230299A - Navigator mounted on vehicle - Google Patents

Abstract

PURPOSE:To shorten a route calculation time by allowing the 1st route calculating means to retrieve a connection node between upper and lower hierarchical layers from a road net data including a current position and allowing the 2nd route calculating means to retrieve a connection node between upper and lower hierarchical layers including a destination to calculate respective routes. CONSTITUTION:The route is calculated by a 1st route calculating means D1 to guide a driver from the current position up to a node included in the prescribed range W2 of the destination and then the detailed route up to the destination is calculated by a 2nd route calculating means D2 to guide the driver up to the destination. Since the calculation of detained routes around an extremely far destination e.g. can be postponed, the whole calculation time can be shortened as compared with a case for calculating detailed routes around the destination from the initial stage, and when conditions on the way of traveling are changed, it is unnecessary to recalculate the route.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a self-contained in-vehicle navigator, and more specifically, to a road map stored in a map memory according to a destination setting by a driver. An in-vehicle navigator that reads road map data in a range including the current location and destination from the data, calculates a recommended route from the current location to the destination based on this road map data, and guides the vehicle along this recommended route. It is something.

<Prior Art> In-vehicle navigators have been known that have been developed to display routes and the like on a screen to facilitate driving in unfamiliar areas or at night.

Conventional in-vehicle navigators include a display, direction sensor, distance sensor, map memory,
A computer is installed in the vehicle and calculates the coordinate position of the vehicle based on the direction change data input from the direction sensor and the mileage data manually input from the distance sensor, and displays this coordinate position on the road map displayed on the screen. The so-called dead-reckoning method that displays duplicate images and the navigator using dead-reckoning described above are further developed to determine the vehicle position on the road based on the degree of correlation between the coordinate position and the road stored in the map memory. A so-called map matching navigation method is known in which the map is displayed superimposed on the road displayed on the screen (see, for example, Japanese Patent Laid-Open No. 148115/1983).

Even with the above-mentioned navigators, in order to guide the vehicle to the destination, it is only necessary to display the vehicle's position and the destination's position on the road map displayed on the screen, and to select the route from the current location to the destination. was left to the driver to decide.

However, in recent years, the driver is required to input the destination and desired route calculation conditions (specifically, the shortest distance route, shortest time route, etc.) before starting the journey, and the travel time or travel distance is set as a parameter. The applicant has previously applied for a navigator that guides a vehicle by calculating the shortest route from the current location to the destination using the so-called Dijkstra method, and superimposing and displaying the calculated route on a road map. (Refer to the specification of Japanese Patent Application No. 1-88441.) As shown in FIG. A map storage means A storing map data, a position detection means B detecting the vehicle position, an initial setting means C for inputting a destination and route calculation conditions desired by the driver, and the above-mentioned map storage means. Read road map data in a range including the current location and destination from A,
A route calculation means for calculating a recommended route based on the road map data and the route calculation conditions set by the initial setting means C; a storage means E for storing the recommended route; and a storage means E for converting the road map data into map display data. , the above recommended route is superimposed on the above map display data, and a road map is displayed on the screen.
It has route guidance means F that displays the current position (vehicle position) and recommended route.

The specification of the earlier application (Japanese Patent Application No. 1-88441) states that the map storage means A stores road data from the highest hierarchical map with the widest node interval to the lowest hierarchical map with the narrowest node interval according to the road type. The recommended route calculation means sets a route search area based on the straight-line distance from the current location to the destination, and if the route search areas are on the same level, A route is calculated by adding the links from a node near the current location to a node near the destination in the hierarchy, and if the route search area is not on the same hierarchy, an interlayer connection node that connects the lower hierarchy and the upper hierarchy. While searching from the road network data, search for a route from a node near the current location to an interlayer connection node on the current location side, a route from a node near the destination to an interlayer connection node on the destination side, and a route from an interlayer connection node on the current location side to the destination. It is disclosed that the route from the nodes near the current location to the nodes near the destination is calculated by summing the routes to the ground-side interlayer connection node (see claim 3 of the specification of the prior application). .

FIG. 1O is a diagram for explaining the route calculation method of the prior invention, and shows the route search area divided into hierarchical maps (three hierarchical levels are illustrated in the figure).

If multiple levels are set as the route search area,
While searching the road network data for the interlayer connection nodes c and d that connect the lower layer M2 and the upper layer M1, the interlayer connection node c1 on the starting point side of the recommended route is searched from the node a near the current location P in the lower layer M2. Then, calculate the route from node b near the destination Q to the destination interlayer connection node d within the same layer, and the distances c and d between the interlayer connection nodes are within the upper layer M1 where the node spacing is set wide. Calculate the route.

In this way, in the invention of the prior application, the upper layer map M1 is used to search for a route between the interlayer connection nodes c and d, which is usually a long-distance route, so when all routes are calculated on the lower layer M2, The time required for route calculation can be reduced compared to

<Problem to be solved by the invention> In the above-mentioned prior invention, node a in the lower hierarchy M2
The route calculations from the interlayer connection node c1 and the interlayer connection node d to the node b, and the route calculation between the interlayer connection nodes c and d in the upper layer M1 are performed continuously in time as a series. was. For example, a route calculation from node a to node C, a route calculation from node C to d, a route calculation from node d to node b are performed in this order, or a route from node a to node C in the lower hierarchy M2. The route calculation from node d to node b was performed first, and then the route calculation from node C to d in the upper hierarchy M1 was performed.

However, for example, when going to a very distant point, it is not necessary to calculate a detailed route around the destination first. Because there is still time to reach the destination,
This is because there is plenty of time to calculate detailed routes around the destination while driving, and if you calculate from the beginning, you may have to recalculate if circumstances change during the journey.

Also, if you calculate a detailed route around the destination from the beginning, it will take more time to calculate, which also has the disadvantage that it will take longer to calculate the route you need for the time being starting from your current location. .

The present invention has been made in view of the above problems, and an object of the present invention is to provide an in-vehicle navigator that can shorten route calculation time as a whole by improving the prior invention.

Means for Solving the Problem>PQ The present invention to achieve the above object, as shown in FIG. A map storage means A that classifies and stores maps from the highest hierarchy map with the widest node interval to the lowest hierarchy map with the narrowest node interval, a position detection means B that detects the vehicle position, and a destination and a driver. Initial setting means C for inputting desired route calculation conditions and road map data of a range including the current location and destination are read from the above-mentioned map storage means A, and the road map data set by this road map data and the initial setting means C are read out. first and second route calculation means D1 and D2 that calculate a recommended route based on route calculation conditions; a storage means E that stores the recommended route; and a storage means E that converts road map data into map display data and displays the map Route guidance means F that superimposes the above recommended route on the data and displays the road map, current position, and recommended route on the screen.
The first route calculation means D1 includes a node N near the current location.
A route search area connecting lower and upper hierarchies is set between Node N5 and node N5 near the destination, and the lower and upper hierarchies are searched from road network data within a predetermined range Wl including the current location. Search for the interlayer connection node N2 on the current location side that connects the current location, and also search for the route between the node N1 near the current location and the interlayer connection node N2 on the current location side in the lower hierarchy, and the interlayer connection node on the current location side in the upper hierarchy. The second route calculation means D2 calculates a route between the node N2 and any node N3 existing within a predetermined range W2 including the destination, and the second route calculation means D2 calculates a route between the node N2 and any node N3 existing within a predetermined range W2 including the destination. Then, from the road network data within a predetermined range W2 including the destination, search for an interlayer connection node N4 on the destination side that connects the upper layer and the lower layer, and perform the first route calculation in the upper layer. Calculate the route between the node N3 specified by the means Dl and the interlayer connection node N4 on the destination side, and the route between the interlayer connection node N4 on the destination side and the node N5 near the destination in the lower hierarchy. It is something.

Effects> According to the present invention, the route calculation procedure can be divided into two stages.

First, the first route calculation means D1 searches the road network data within a predetermined range Wl including the current location for an interlayer connection node N2 on the current location side that connects a lower hierarchy and an upper hierarchy, and A route between the node N1 near the current location and the interlayer connection node N2 on the current location side is calculated. As a result, node N1 near the current location in the lower hierarchy
The route between the node N2 and the interlayer connection node N2 on the current location side can be determined at a relatively detailed level in the lower hierarchy.

Furthermore, route calculation between the interlayer connection node N2 on the current location side in the upper hierarchy and the destination or the node closest to the destination on the upper hierarchy is started. At this time, if any node N3 within the predetermined range W2 from the destination is reached, the calculation for route guidance is terminated.

As a result, from node N2, W within a predetermined range from the destination
This means that the route to node N3 within No. 2 has been determined, and the route guidance means F guides the driver for the time being.

Next, when the vehicle approaches the destination, the second route calculation means D2 calculates the route to the destination.

That is, the interlayer connection node N4 on the destination side that connects the upper layer and the lower layer is connected to a predetermined range W2 including the destination.
In addition to searching from the road network data in
3, and the route between the node N5 near the destination in the lower layer and the interlayer connection node N4 on the destination side. Thereby, the driver can be guided from node N3 to the destination.

Note that in each of the above procedures, the interlayer connection node search and route calculation may be performed first and the route calculation may be performed later, or both may be performed in parallel.

In addition, in the second route calculation means D2, the route calculation between the node N4 and the node N3 in the upper layer or the route calculation between the node N5 and the node N4 in the lower layer may be performed first. good.

Furthermore, in the first route calculation means D1 and the second route calculation means D2, the route calculation between nodes may be performed in any direction. In other words, calculations may be performed using the node near the current location as the starting point and the node far from the current location as the ending point.Conversely, the calculation may be performed using the node near the destination as the starting point and the node far from the destination. The calculation may be performed with .

<Embodiments> Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings.

FIG. 2 is a block diagram showing the in-vehicle navigator.

The in-vehicle navigator includes a display 1, a console 2, a map memory 3, a memory drive 4, a touch panel 5, an initial setting section 6, a processing section 7, a main memory 8, a distance sensor 9, a direction sensor 10, a locator 11, an output controller 12, and It has a human output interface 13. Furthermore, a communication device 14 for receiving road information transmitted from a control station and an audio output device 15 for notifying that the vehicle is approaching a branch point may be provided.

The display 1 displays an initial setting menu, a road map, vehicle positions, recommended routes, etc. at predetermined dot positions in arbitrary color gradations. As this display 1,
CRT, liquid crystal panel, etc. can be used.

The console 2 has a keyboard board (not shown) for starting and stopping the device, moving a cursor on the screen, manually scrolling the road map displayed on the screen, etc.

The map memory 3 divides the road map into meshes, and stores road data consisting of combinations of nodes and links and road map data consisting of background data such as buildings and the like for each mesh.

This road map data is used for graphic display and route calculation. This map memory 3 is a CD-R
Mass storage media memory such as OM, IC memory card, magnetic tape, etc. can be used.

To explain the map memory 3 in more detail, the map memory 3 has a first partition that divides the Japanese road map into sections with a difference in longitude of 1 degree and a difference in latitude of 40 minutes, and the vertical and horizontal distances are approximately 80 km x 80 -.
The next mesh (see Figure 5 (C)) and the second mesh (see Figure 5 (D)), which divides this first mesh into 8 equal parts vertically and horizontally, and divide the horizontal and vertical distances into approximately lOK-X 10. ), and a third mesh (see FIG. 5(E)) in which this second mesh is further divided into 10 equal parts and the vertical and horizontal distances are approximately IKmXIK-. Then, from the first mesh to the third
The road network data of the next mesh is ranked into three levels from the first level to the third level, and the roads in the first level are composed of expressways and main arterial roads. The roads in the second hierarchy are composed of the roads in the first hierarchy plus general arterial roads, and the roads in the third hierarchy are composed of all streets including narrow streets (community roads).

A node consists of a branch point node and an auxiliary node placed between the branch points. The node data includes a node number, an address of an upper, lower, or adjacent mesh node corresponding to the node number, an address of an adjacent node, an address of a link connected to the node, and the like.

The link data includes the link number, the addresses of the start and end nodes of the link, the distance of the link, the time required to travel the link, and the type of road (expressway, main road, etc.).
(city roads, etc.), road width, traffic regulations such as direction traffic and toll roads, etc.

The background data includes railways, rivers, place names, famous facilities, points registered in advance by the driver, contour lines, etc. In principle, the contour height r' is not displayed, but is used when setting the route mode.

Note that the above-mentioned node intervals can be set to even narrower intervals depending on the capacity of the map memory 3 and the processing speed of the processing section 7.

FIG. 4A is a diagram three-dimensionally showing the positional relationship between the first hierarchy and the second hierarchy. The explanation of the symbols is as follows.

P: Vehicle current position N1: A node near the current location at the point on the link where the perpendicular line from the current location P to the link on the second hierarchy is the shortest, Nl A predetermined range W1 on the second hierarchy that includes the current location P
An interlayer connection node existing within N3; any node existing within a predetermined range W2 including the destination Q found as a result of route calculation from the interlayer connection node N2 on the current location side in the first hierarchy; Q: Destination N5: A node near the destination at the point on the link where the perpendicular line from the destination Q to the link on the second hierarchy is the shortest, N4: A predetermined range including the destination Q on the first hierarchy W
An interlayer connection node existing within 2.

In addition, the route J1 includes nodes N1 to N in the second layer.
The route J2, which is the route calculated between the two nodes, is the route calculated from the node N2 to the destination Q in the first hierarchy, and the calculation is terminated at the node N3. Route J3 is a route calculated between nodes N3 and N4 in the first hierarchy, and route j4 is a route calculated between nodes N4 and N5 in the second hierarchy. Route J5 is a route calculated when node N4 or route J4 in the second layer is not found.

The touch panel 5 is attached to the screen of the display 1, has transparent electrodes arranged in a matrix, and outputs touch positions by the driver to the initial setting section.

The initial setting unit 6 displays a road map or the like on the display 1 for setting a destination, and allows the driver to touch the display position to select the destination and a desired route mode (a mode that prioritizes the shortest route, a mode that prioritizes the shortest route, etc.). A mode that prioritizes the distance route, a mode that prioritizes the shortest cost, a mode that minimizes the number of left and right turns, etc.) can be set.

In addition, the initial setting section 6 displays types of display modes, such as a rotation mode in which the vehicle's traveling direction is fixed and the surrounding map is rotated, and a fixed mode in which the map is fixed in the north direction, and allows the driver to select the desired display mode. You may also touch the display mode position. Note that the destination information may be entered manually by operating keys on the console 2. In this case, point data such as a place name map of a road map, a column of famous facilities, points registered in advance by the driver, etc. may be selected and input. It is also possible for the driver to specify the intermediate points on the way.

The processing unit 7 performs route calculation and route guidance, and when calculating the route, it uses the evaluation function Fi corresponding to the route mode set by the driver to move from the starting point node to the ending point node based on Dijkstra's method. Calculate the recommended route to reach the destination. Further, the weighting set by the driver changes the contents of the evaluation function Fl according to the value of the index αm, and a recommended route from the start point node to the end point node is calculated based on the changed evaluation function.

The main memory 8 temporarily stores the recommended route calculated by the processing unit 7.

The σ digitizer 11 has a map memory lla for position detection and a microcomputer llb. The map memory lla for position detection stores addresses of dividing nodes, branch nodes, and adjacent nodes in relation to each node, which are obtained by dividing all roads within a predetermined range into each predetermined distance. The node positions are set to approximate the roads on which the vehicle actually travels. In addition, the microcomputer 1
1b calculates travel trajectory data by integrating the distance data detected by the distance sensor 9 and the direction change data detected by the orientation sensor 10, and stores the travel trajectory data and the position detection map memory 11a. The vehicle position is detected based on the degree of correlation with the existing road pattern. The orientation sensor 10 detects changes in orientation as the vehicle travels, and uses a geomagnetic sensor, a gyro, a wheel speed sensor that detects a turning angle based on the difference in rotational speed between the left and right wheels, and the like. Is possible.

Further, the distance sensor 9 detects the traveling distance based on the speed of the vehicle or the number of rotations of the wheels, and a wheel speed sensor, a vehicle speed sensor, etc. can be used. Note that it is also possible to use the map memory lla for position detection and the map memory 3 in common.

FIG. 3 is a diagram showing the hardware configuration of the processing section 7, main memory 8, and output controller 12, in which the path line 16 includes the main memory 8, the first ROM 17 storing the program for path calculation, and the path line 16. A second ROM 18 that stores a guidance program, a first cPU 19 that calculates a recommended route and provides route guidance based on a route calculation program and a route guidance program, an input/output interface 13, and a second CPU 20 for display are connected. has been done. A frame memory 21 is installed in the second CPU 20 for the above display.
is connected. In addition, the input/output interface 13
A communication device 14 and an audio output device 15 are connected to.

That is, the first ROM17, the second ROM18, the first CP
U19 performs route calculation and route guidance. 2nd CPU
20 and a frame memory 21, the output controller 12 displays a road map or the like in a predetermined format.

The first CPU 19 sets the above-mentioned evaluation function according to the selected or changed route mode from the initial setting section 6. Also, depending on the set destination, the starting point node,
and the road network data including the end node are stored in the map memory 3 (
(using the first layer or the second layer).

Next, a recommended route from the starting point node to the ending point node is calculated based on the evaluation function set above. Additionally, a new recommended route is calculated based on information such as traffic congestion manually input from the communication device 14. Then, the calculated recommended route is temporarily stored in the main memory 8, and each time the vehicle approaches a start node, an end node, or a branch point stored in the main memory 8, the road including the branch point is stored in the map memory 3. Reads the map data, converts the read road map data into rotational display data for displaying the data by rotating it around the vehicle position, converts the format into a display mode with good visibility, and transfers it to the output controller 12. are doing. Additionally, a warning sound indicating that the vehicle is approaching a fork and route instructions are output to the audio output device 15.

The second CPU 201 writes the road map data format-converted by the first cPU 19 into the frame memory 21 and displays it on the display 1.

The operation of the in-vehicle navigator having the above configuration will be explained based on the initial setting screen display diagram in FIG. 5 and the route guidance flowchart in FIG. 6.

First, in step (1) of FIG. 6, the driver selects the destination and the desired route mode (the shortest route priority mode, the shortest distance route) by touching the initial setting screen displayed on the display 1. mode to prioritize,
Set a mode that prioritizes the shortest cost, a mode that minimizes the number of left and right turns, etc.

To explain this procedure in detail,
To calculate the route, touch the desired mode position among the displayed modes such as the mode that gives priority to the route with less travel time, the mode that gives priority to the route with short travel distance, the mode that gives priority to the route with less travel cost, etc. Specify the mode (5th
(See figure (A)).

■1 Next, the driver is asked via the screen whether or not the weighting index should be changed. If the answer is No, a recommended route is selected in the previous mode. If the answer is YES, the weighting index α■ and the number for setting the index α■ are displayed. The driver touches the number position (see FIG. 5(B)).

(2) The weighting of the evaluation function Fi changes the index α■.

■Display the road map of the first layer on one screen.

(See Figure 5 (C)) ① Touch the mesh location (Taito Ward in the drawing) that includes the destination on the first level. Then the specified mesh (
A road map of the entire Taito Ward is displayed (see Figure 5 (D)).

■Touch the mesh location that includes the destination on the second level (in the drawing, the block that includes Ueno Park). This designated mesh position may be used as the destination. Next, a road map of the center of the specified mesh will be displayed.

(2) Search for the destination by scrolling the 3rd layer road map, and touch the destination position (see FIG. 5(E)).

After the initial setting input has been made as described above, the display returns to the current location, and the vehicle position P from the locator 11 is displayed.
, and the aforementioned destination Q are input, and a first recommended route calculation (referred to as route calculation A) is performed (step (2)).

Route calculation A is performed before the vehicle starts and at any time while the vehicle is running, and its contents are as follows.

FIG. 7 is a flowchart of route calculation A.

The calculation may be performed before the vehicle starts or may be recalculated while the vehicle is running.

In step (21>, the vehicle position P1 and the aforementioned destination Q from the locator (11) are input. In step (22), when the current location P and the destination Q are on a narrow street, the automatic search target The node on the general highway on the second level hierarchy closest to the current location P is set as the starting point node N1, and the node on the general main road closest to the destination Q is set as the ending point node N5. , current location P
or destination Q is on a narrow street other than a main road, the starting point is node N1, which is the point on the main road with the shortest perpendicular line from the current location P to the nearest main road on the secondary hierarchy, and The end point is node N5, which is the point on the trunk line with the shortest perpendicular line from ground Q to the nearest trunk road on the second hierarchy. Of course, when the start point and end point are on a narrow road, the start point node N1 and the end point node N5 are placed on the road segment of the third layer.
It is also possible to set the route, but if narrow streets are also included in the guidance, the route will be directed to community roads, so as a general rule, it is better to target general arterial roads (routes on the second level hierarchy). Further, when the current location P and the destination Q are on a general highway, the current location P is set as the starting point node Nl, and the destination Q is set as the ending point node N5.

In step (23), the straight line distance X from the current location P to the destination Q is a predetermined distance Lo (this distance).

is about 20 km in the city center and about 30 km in the suburbs.
If it is determined that it is shorter than 1 Lo, step (
In step 20, a small square area W5 including the destination Q (this area w5 is for determining whether the vehicle has reached the destination Q) is set on the second hierarchy, and step (25 ), a rectangular area on the second hierarchy including the current location P5 and the destination Q is set (see FIG. 4B).

At this time, the first layer map is not used. Step (
In 2B), a recommended route on the second hierarchy is calculated based on the evaluation function Fmi corresponding to the previously set route mode. At this time, if traffic information such as congestion, accidents, road construction, etc. is obtained from the control station, a recommended route is calculated that takes that information into consideration (the same applies to the route calculations below).
.

In step (27), it is determined whether the recommended route to the end point node N5 on the second hierarchy has been calculated, and if it is determined that the recommended route has not been calculated, in step (28), a rectangular The area is enlarged, and steps (26) to (27) are performed.

In this case, the number of times the area is expanded is set in advance to prevent an endless loop.

If it is determined in step (27) that the recommended route has been calculated, the process returns to the flow shown in FIG. 6. In this way, the route search area from the current location P to the destination Q is
If it seems possible to do the calculation in a short time even if it is calculated in the same layer because P and Q are close, etc., add the link from node N1 near the current location to node N5 near the destination in the same layer. and calculate the route.

However, in step (23) above, if it is determined that the straight line distance 2nd layer).

First, in step (30), a square area W2 including the destination Q is set on the first hierarchy. This square area is used for route calculation on the first level (step (
36) and (54)). Step (
In 31), a square area W1 including the current location P is set on the second hierarchy. Generally, the size of area W1 is
It is set small in the city center and large in the suburbs.

In step (32), the first layer is searched to find the starting point side interlayer connection node N2, and a recommended route from the starting point node N1 to the starting point side interlayer connection node N2 is calculated based on the evaluation function F1. In step (33), it is determined whether the recommended route from node N1 to N2 has been calculated, and if it is determined that the recommended route has not been calculated, the square area W1 is expanded in step (34), and the square area W1 is expanded in step (34). (32).

Perform the process (33). Even in this case, the number of times the area is expanded is limited to avoid an endless loop.

In step (33), if it is determined that the recommended route to the starting point side interlayer connection node N2 has been calculated, in step (35), the route is moved up to the first layer,
A rectangular area WO for defining a route calculation range is set. In step (36), the evaluation function Fat set the recommended route from the starting point side interlayer connection node N2 to the area W2.
Calculated based on.

In step (37), the square area W2 on the end point side
has been reached (that is, whether one of the tips of the candidate route being calculated has entered the square area W2),
If it is determined that it has not reached the rectangular area WO
Expand step (38)), step (35) (3
Repeat the process of 6). In this case, the method of preventing an endless loop is the same as described above. Step (37
), if it is determined that the square area W2 on the end point side has been reached, the arrival point (node N3) is specified and the sixth
Return to the diagram flow.

Note that in the above route calculation A, the calculation was aborted if it was determined in step (37) that the square area W2 on the end point side was reached, but instead of being aborted, the calculation was stopped at the end point node N5 or its vicinity on the first hierarchy. The recommended route J5 to the node may be calculated in advance. This is because the recommended route J5 may need to be calculated depending on the conditions in the flowchart of FIG. 8, which will be described later, so if it is calculated in advance at this stage, the time for later calculations can be saved.

As described above, according to the flowchart of the recommended route calculation A, the area of the second layer is shortened based on whether the straight line distance from the current location P to the destination Q is larger or smaller than the predetermined distance Lo. Rectangular area for distance route calculation (4th
(Figure B) or square area W1 for long-distance route calculation
limited to.

In the case of short-distance route calculation in steps (24) to (28), the main road network data within the rectangular area is read out, road segments within the limited area are added, and the data is calculated from the starting point node N1 to the ending point node. A route can be calculated to N5.

In addition, in the case of long-distance route calculation in steps (30) to (84), in the same way as in the case of short-distance route calculation described above, in the square area W1, the starting point node N1 and the starting point side are The route between the interlayer node N2 is calculated, and the route between the starting point side interlayer connection node N2 and the end point side square area W2 is calculated within the upper layer, which is roughly set such as the main arterial road. Even if the route is a long distance, the time required for route calculation can be reduced.

Thereafter, the process returns to steps (3) to (9) in FIG. 6 to enter the actual route guidance procedure. In step (3),
A wide range of roads centered around the vehicle is displayed together with the vehicle position (see FIG. 5(F) for a display example).

Next, in step (4), it is determined whether the vehicle is located on the recommended route.

The display process in step (3) continues until the vehicle is located on the recommended route.

If the vehicle is located on the recommended route, in step (5) the vehicle moves to the square area W2 of the recommended route (in the case of short-distance route calculation).
Alternatively, it is determined whether or not W5 (in the case of long-distance route calculation) has been reached, and the process proceeds to step (6) and subsequent steps until the square area W2 or W5 is reached. Step (6
), it is determined whether the vehicle has approached the branch point where guidance is to be provided.

As long as they do not approach, the display process in step (3) continues.

When approaching a branch point, a road map in a range including the number of branch points to be displayed set by the initial setting section 6 is read from the road map memory (step (7)). Note that the process in step (7) may be performed in advance before the vehicle approaches the branch point.

In step (8), based on the road map read out in step (7), an enlarged view of the branch point is created, centering on the branch point where guidance is to be provided.

In step (9), the enlarged view of the branch point is displayed on the display 1 at a predetermined enlargement ratio.

Thereafter, the processes from step O) to step (9) are repeated.

During the repetition, after it is determined in step (5) that the square area W2 or W5 has been reached, step (
1O) and determine whether the square area is W2 or W5.

In the case of area W5, the route guidance is ended because the route guidance has come very close to the node N5 on the second hierarchy which is closest to the destination Q, and there is no need to perform further route guidance.

If the area is W2, route calculation B in FIG. 8 is performed in step (11).

The route calculation B shown in FIG. 8 will be explained in detail below. This route calculation B
Now, an example will be shown in which the recommended route is calculated in the reverse direction starting from the end point node N5. In step (51), a square area W3 is set on the second hierarchy for calculating a route from node N5. The size of this area W3 may be wider or narrower than the size of area W2. However, considering the efficiency of searching for interlayer connection node N4, W3
preferably contains W2. Of course, the size may be the same as the area W2. This is area W3
This is because the purpose of route calculation is different between area W2 and area W2.

In step (52), a recommended route from node N5 to end point side interlayer connection node N4 is set in area W3 while searching for end point side interlayer connection node N4 connected to the first layer in square area W2. It is calculated based on the evaluation function Fl.

In step (53), it is determined whether a recommended route from node N5 to end-point side interlayer connection node N4 has been calculated, and if it is determined that a recommended route has not been calculated, the route is backward calculated from node N5. Abandoning the process of route calculation B, and proceeding to step (56), the recommended route J5 from the node N3 on the first layer to the point on the link closest to the destination Q on the first layer is calculated. Then, the process returns to the flowchart in FIG.

If it is determined in the step (53) that the recommended route J4 to the node N4 has been calculated, in the step (54), the route search area W on the first hierarchy is
2, a recommended route from node N4 to node N3 is calculated based on the set evaluation function F1. If the recommended route up to the node N3 has not been calculated, the process moves to step (56) as described above, where the recommended route J5 is calculated, and the process returns to the flowchart of FIG. 6. When the recommended route to node N3 has been calculated, the process immediately returns to FIG. 6.

As described above, in the case of long-distance route calculation, when the vehicle enters the square area W2 on the first layer, the recommended route calculation from the destination nearby node N5 to the end point side inter-layer connection node N4, A recommended route from connection node N4 to node N3 is calculated for the first time, and route guidance and guidance are provided.

Therefore, before and after starting the vehicle, the driver only needs to first calculate the necessary route from the current location P, which shortens the time it takes to start route guidance and route guidance after starting the vehicle. Compared to calculating all routes, it is easier to deal with changes in conditions during the trip.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments.

For example, the shape of each of the square areas W1 to W3 is not limited to a square, but may be rectangular, circular, or the like. Various design changes can be made without changing the gist of the invention.

<Effects of the Invention> According to the present invention described above, first, the first route calculation means D1
By calculating the route, the driver is guided from the current location to a node within the predetermined range W2 of the destination, and then the detailed route calculation means D2 to the destination is calculated by the route calculation means D2 of Section 2, and the driver is driven. can guide people to their destinations.

Therefore, for example, when going to a very far point, the calculation of the detailed route around the destination can be postponed, compared to the conventional case where the calculation of the detailed route around the destination is done from the beginning. , the overall calculation time can be shortened, and there is no need to recalculate due to changes in circumstances during the trip.

[Brief explanation of drawings]

Fig. 1 is a functional block diagram of the in-vehicle navigator of the present invention, Fig. 2 is a block diagram showing an embodiment of the in-vehicle navigator of the present invention, and Fig. 3 shows the hardware configuration of the processing section, main memory, output controller, etc. Figure 4A is a diagram showing the three-dimensional relationship between the upper diagram of the first hierarchy and the upper diagram of the first hierarchy, Figure 4B is a diagram showing the route search area in the case of short-distance route calculation, and Figure 5 ( A) to (F) are diagrams showing the initial setting menu and map display displayed on the screen, Figure 6 is a diagram showing the recommended route guidance flow, Figure 7 is a diagram showing the flow of route calculation A, and Figure 8 9 is a block diagram of the in-vehicle navigator according to the earlier application, and FIG. 10 is a diagram for explaining the route calculation method of the invention of the earlier application. Dl...first route calculation means, D2...second route calculation means

Claims (1)

[Claims] 1. Road data consisting of combinations of nodes and links is classified according to the road type from the highest hierarchical map with the widest node spacing to the lowest hierarchical map with the narrowest node interval. A map storage means A that stores the map, a position detection means B that detects the vehicle position, and an initial setting means C that inputs the destination and route calculation conditions desired by the driver.
and a first step that reads road map data in a range including the current location and destination from the map storage means A, and calculates a recommended route based on this road map data and the route calculation conditions set by the initial setting means C. and a second route calculation means D1, D2, and a storage means E for storing the recommended route, which converts the road map data into map display data, superimposes the recommended route on the map display data, and displays a road map on the screen. , a route guidance means F for displaying the current position and a recommended route, and the first route calculation means D1 includes a node N near the current location.
A route search area connecting lower and upper layers is set between Node N5 and node N5 near the destination, and the lower and upper layers are determined from road network data within a predetermined range W1 including the current location. Search for the interlayer connection node N2 on the current location side that connects the current location, and search for the route between the node N1 near the current location in the lower hierarchy and the interlayer connection node N2 on the current location side, and the interlayer connection node on the current location side in the upper hierarchy. The second route calculating means D2 calculates a route between N2 and any node N3 existing within a predetermined range W2 including the destination, and when the vehicle approaches the destination, the second route calculating means D2 From road network data within a predetermined range W2 including the destination, search for an interlayer connection node N4 on the destination side that connects an upper layer and a lower layer, and at the same time search the first route calculation means D1 in the upper layer. The route between the node N3 identified in and the destination-side interlayer connection node N4, and the destination-side interlayer connection node N4 in the lower hierarchy.
An in-vehicle navigator characterized in that it calculates a route between a node N5 and a node N5 near a destination.