JP2000283777A - Car-carried navigation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a car-carried navigation system capable of retrieving routes at a high speed. SOLUTION: A navigation system separately stores map drawing data 2a for writing a map image on a display screen and road network data 2b for retrieving routes, and divides the road network data 2b in a plurality of areas each having an approximately equal data quantity for easing the data cache or look-ahead wherein the road network data 2b includes areas having all specified highway road data and is updated per area as a unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle navigation device, and more particularly to a method for storing map data necessary for performing various processes such as map display and route search.

[0002]

2. Description of the Related Art In an on-vehicle navigation device, data relating to drawing required for displaying a map and data relating to roads required for a route search are used as map data as C data.
It is stored and provided on a medium such as a D-ROM or a DVD-ROM. In this map data, a map data storage method of storing rectangular areas of equal area separated by a predetermined longitude and latitude as a unit, and a data area divided by a predetermined data amount instead of a rectangular area of an equal area as a unit. There is a map data storage method for storing the obtained rectangular area as a unit. For example, FIG. 7 is a diagram showing map data divided into equal areas that store rectangular regions separated by predetermined longitude and latitude as units. The map is divided by predetermined longitude and latitude, and the divided rectangular area is called a map leaf, and a number is assigned to each map leaf.

[0003]

However, in the case of the above-described map data storage method in which the rectangular area divided by the predetermined longitude and latitude is stored in the same area as a unit, the data amount of the figure divided into the rectangular area However, there is a problem that it is difficult to control data caching, prefetching, and the like by an application in a navigation device having a limited memory because the data is different in an urban area and a suburb. Also, in the case of the map data storage method in which a rectangular area divided by a predetermined data amount is stored as a unit, a network for connecting data divided into rectangular areas has a complicated structure, and it takes time to decode. There's a problem. Further, in these map data storage methods, drawing data relating to map drawing and road network data for route search are stored in a data structure in which they are integrated. For this reason, when a road is newly established, changed, or deleted, it is necessary to update the data related to the road, including the drawing data related to the map drawing, and it takes time to update the data. is there. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide an on-vehicle navigation device capable of performing a route search at high speed.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a road search route network data including link sequence data relating to a link sequence in which one or more links as minimum units representing a road shape are connected. An on-vehicle navigation device having map data storage means for separately storing drawing data to be drawn on a display screen, and route search means for performing a route search based on the road network data stored in the map data storage means. In the above, the road network data for route search is solved by being divided into a plurality of regions having a substantially uniform data amount. Further, according to the present invention, the above-mentioned object is achieved by that the road network data for route search includes an area having all of predetermined expressway data. In addition, according to the present invention, the above object is achieved by updating the road network data for route search in units of the area.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) Configuration of Navigation Apparatus FIG. 1 is a diagram showing the configuration of an on-vehicle navigation apparatus according to the present invention. The navigation device includes a navigation controller 1 for controlling the whole, and a CD-ROM or DVD storing map data necessary for map drawing, route search, and the like.
A storage medium 2 such as a ROM, a disk reading device 3 for reading map data stored in the storage medium 2, a remote control (remote control) unit 4 as an operation unit for a driver or a passenger to input various instructions. A GPS receiver 5 and an autonomous navigation sensor 6 for detecting a vehicle position and a vehicle direction, a display device 7 for displaying a map image and a guidance route superimposed on the map image, and outputting a predetermined guidance voice when performing the route guidance And an audio unit 8 for performing the operation.

The disk reader 3 can load one or a plurality of storage media 2, and reads out map data from any of the storage media 2 under the control of the navigation controller 1. Further, the remote control unit 4 includes a search key for giving a route search instruction, a route guidance mode key used for setting a route guidance mode, a destination input key, left / right / up / down cursor keys, a map reduction / enlargement key, and a display screen. Various operation keys such as a setting key for fixing an item at a cursor position are provided, and an infrared signal according to an operation state of the key is transmitted to the navigation controller 1.

The GPS receiver 5 receives radio waves transmitted from a plurality of GPS satellites, performs three-dimensional positioning processing or two-dimensional positioning processing, and calculates the absolute position and azimuth of the vehicle (the azimuth of the vehicle is at the present time. Is calculated based on the vehicle position and the vehicle position one sampling time ΔT before), and these are output together with the positioning time. In addition, autonomous navigation sensor 6
Is provided with an angle sensor 11 such as a vibrating gyroscope that detects the vehicle rotation angle as a relative direction, and a distance sensor 12 that outputs one pulse for each predetermined traveling distance, and detects the relative position and direction of the vehicle.

The display device 7 displays map information around the vehicle based on image data output from the navigation controller 1 together with a vehicle position mark, a departure point mark, a destination mark, a landmark (facility mark), and the like. , And a guidance route is displayed on the map. The audio unit 8 outputs a guidance voice at an intersection where the vehicle is approaching.

(2) Detailed contents of map data The map data stored in the storage medium 2 includes map drawing data 2a stored in units of rectangular areas separated by predetermined longitude and latitude, and predetermined data. And road network data 2b for route search stored in units of polygonal areas divided by quantity. As shown in FIG. 2 (a), the map drawing data 2a is a unit of a map leaf separated by a predetermined longitude and latitude, and a plurality of map drawing data of each map leaf are provided in accordance with the area size. 2B. As shown in FIG. 2B, the map drawing data of each leaf includes a drawing unit. Also, the map drawing data of each figure can be specified and read by designating the figure number. The drawing unit is composed of various data necessary for drawing a map. For example, the drawing unit contains background layer data necessary to draw buildings, terrain, coastlines, rivers, etc.
The data includes character layer data necessary for displaying landmarks and the like, and drawing road data necessary for displaying roads and the like on a display screen.

Road network data 2b for route search
Is stored in units of a polygonal area divided by a predetermined data amount, for example, 512 Kbytes or less, for each layer. The road network data of the layer 0 is shown in FIG.
As shown in (1), a unit is a polygonal area (hereinafter, referred to as “section”) divided by a predetermined data amount. Each section has a hierarchical structure based on the amount of information of the road network. The layers are expanded from a lower layer with more information on the road network to an upper layer with less information on the road network, and have connection information between the layers. ing. FIG. 4 is a diagram showing a hierarchical structure of road network data. For example, if the road data is “Expressway, 1
If the road network data is divided into four levels: ~ 2 digit national roads, "other national roads,""localroads," and "other general roads," the road network data for each section will be divided into two levels,
Level 3 is the road network data of "Expressways, 1-2 digit national roads"
Level 2 is road network data obtained by adding "other national roads" to level 3 road network data, level 1 is road network data obtained by adding "local roads" to level 2 and level 3 road network data, and level 0 is level This is road network data obtained by adding “other general roads” to the road network data 1 to 3, and is classified into four layers and managed. As shown in FIG. 3 (b), a section of level 3 "highway, 1-2 digit national highway", which is a main road, is provided for each same motorway, for example, section No. 301 for the Tohoku Expressway or Tomei Automobile. It is also possible to configure a section like the section No. 302 for roads. In this way, it is possible to reduce the number of sections of the road network to be read when performing a long-distance search. For example, when searching for a route between Morioka and Nagoya, section No. 301 including the Tohoku Expressway
By reading the two sections No. 302 including the Tomei Expressway and the Tomei Expressway, long-distance search is possible and the search time is shortened.
Further, as shown in FIG. 5, the road network data of each section is composed of road units composed of data necessary for the route search processing, and the data amount of each section for each layer is equal to or less than the predetermined data amount. I do.

In the above-mentioned road unit, each point of the road network expressing connection, type, regulation, and the like of the road is called a node, and represents a turning point or an intersection of the road. A vector with a direction connecting nodes is called a link. The road unit indicates a unit identification code for identifying the unit, a unit header including data indicating a road level of the section and data of a figure number corresponding to the section, and a storage position of a connection node list. A node table, a connection node list storing detailed data of all nodes, and a link table storing detailed data of a link specified by two adjacent nodes are included.

FIG. 6 is a diagram showing the detailed contents of various tables included in the road unit. As shown in FIG. 6A, the node table stores node records # 0 and # corresponding to all nodes included in the section of interest.
1,. . . Is stored. Each node record is provided with a node number in order from # 0 in the arrangement order, and indicates a storage position of a connection node table corresponding to each node record.

As shown in FIG. 6B, the connection node table includes, for each of the existing nodes, a. Normalized longitude / latitude, b. An "internode node flag" indicating whether or not this node is an intersection node, an adjacent node flag indicating whether or not this node is a node at a boundary with another section, and the like; c. "The number of connected nodes" indicating the number of nodes forming the other end of each link when there is a link having this node as one end of the link; d. No right turn or U
If there are traffic restrictions such as turn prohibition, the "number of traffic restrictions", e. Connection node records for the number of links indicating the link number of each link having this node at one end; f. A traffic regulation record indicating the specific content of the traffic regulation corresponding to the number of the traffic regulations, if any, g. If this node is a node at a boundary with another section, an "adjacent node record" indicating the position of the connection node table of the corresponding node of the adjacent section; h. When this node is an intersection node, the storage location and size of the corresponding intersection record in the intersection unit are included.

As shown in FIG. 6C, the link table includes a plurality of link records in the order of link numbers corresponding to all links included in the section of interest. Each of these link records: a. A link ID, which is a code assigned to each link mainly for a search route, b. Node number 1 and node number 2 identifying two nodes located at both ends of the link; c. Link distance, d. The cost, in minutes, required to traverse this link; e. Various road attribute flags including attribute information of the road corresponding to this link; f. A road type flag indicating the type of road such as whether the actual road corresponding to this link is an expressway or a general road, and the width of the road such as how many meters wide; g. The route number assigned to the road corresponding to this link is included.

(3) Detailed Configuration of Navigation Controller and Route Searching Operation Next, a detailed configuration of the navigation controller 1 shown in FIG. 1 will be described. The navigation controller 1 includes a map buffer 21 for displaying a predetermined map on the display device 7 based on the map data read from the storage medium 2, a map read control unit 22, a map drawing unit 23, a VRAM 24, a read control unit 25, Image synthesis unit 26
A data storage unit 27, a vehicle position / azimuth calculation unit 28 for performing calculation of the vehicle position, map matching processing, route search processing, and route guidance processing and displaying the results.
A map matching processing unit 29, a route search processing unit 30, a route search memory 31, a guidance route memory 32, a guidance route drawing unit 33, a mark image generation unit 34, an intersection guidance unit 35,
A remote control unit 36, a cursor position calculator 37, and an operation screen generator 38 for displaying various operation screens for the user and transmitting operation instructions from the remote controller unit 4 to each unit are provided.

The map buffer 21 includes the disk reader 3
Is for temporarily storing the map data read from the storage medium 2. Map reading control unit 2
2, the instruction to read map data in a predetermined range including the center position of the screen is sent from the map reading control unit 22 to the disk reader 3, and the map display data and the map display data necessary for the map display are transmitted. The drawing road data is read from the storage medium 2 and stored in the map buffer 21. For example, map display data of nine leaves including the screen center position is read and stored in the map buffer 21.

The map drawing section 23 creates a map image necessary for display based on the drawing units included in the map display data of the nine figures stored in the map buffer 21.
The created map image data is stored in the VRAM 24,
The reading control unit 25 reads one screen of map image data. The image synthesizing unit 26 adds the mark image generating unit 34 and the intersection guidance unit 3 to the read map image data.
5. The image data output from each of the operation screen generators 38 is superimposed to perform image synthesis, and the synthesized image is displayed on the screen of the display device 7.

The data storage section 27 sequentially stores positioning position (own vehicle position) data output from the GPS receiver 5. Further, the vehicle position / azimuth calculation unit 28 calculates the absolute own vehicle position and azimuth from the relative position and azimuth of the own vehicle output from the autonomous navigation sensor 6. The map matching processing unit 29 includes a vehicle position or vehicle position / azimuth calculation unit 28 by the GPS receiver 5 stored in the data storage unit 27.
Then, it is determined whether or not the own vehicle position calculated on the road in the map data exists on the road, and if the own vehicle position deviates from the road, a process of correcting the calculated own vehicle position is performed.

When the cursor is moved to a specific location on the map by operating the cursor keys of the remote control unit 4 and the destination input key is pressed, the route search processing unit 30 at this time, the cursor position calculation unit 37 Is set as the destination of the route search. The set destination data is stored in the guidance route memory 32. When the search key of the remote control unit 4 is pressed, the route search processing unit 30 sets the own vehicle position corrected by the map matching processing unit 29 as a departure place, and stores it in the guidance route memory 32. Next, the level of the road network data 2b is set to level 0, and the storage medium 2
, A rectangular area including the starting point and the destination is set, the number of sections including a part or all of the rectangular area is counted, and the number of sections is set to a predetermined value (= storage data capacity of map buffer 21 / per section) It is determined whether or not the number of sections falls below the predetermined value by determining whether or not the number of sections falls below the predetermined value. The hierarchy is set as a route search level. Next, the road network data 2b of the route search level included in the search area is read out, and the map buffer 21
A search is made for a traveling route that connects the departure point and the destination stored in the guidance route memory 32 under predetermined conditions. For example, under various conditions such as the shortest time, a guidance route that minimizes the cost is set. The guidance route set by the route search processing unit 30 in this way is stored in the guidance route memory 32.

The guidance route drawing unit 33 stores the guidance route memory 3
2 from the guidance route data stored in
Those included in the map area drawn on the RAM 24 are selected, and a guidance route which is superimposed on a map image with a predetermined color and emphasized thickly is drawn. The mark image generating unit 34 generates a vehicle position mark at the vehicle position after the map matching processing, or generates a cursor mark having a predetermined shape.

The intersection guide section 35 performs image guidance and voice guidance at an intersection where a vehicle is approaching. When an actual route is being guided, the own vehicle is located within a predetermined distance from an intersection ahead of the guidance route to be turned. Guide map of this approaching intersection when approaching (enlarged intersection, arrow in the direction of travel)
Is displayed on the screen of the display device 7 and the traveling direction is guided by audio through the audio unit 8.

According to the present embodiment, the storage data capacity of the map buffer 21 and the default data capacity of each section are predetermined, and the maximum number of sections that can be read into the map buffer 21 can be known in advance. This has an effect that the prefetch control of the road network data is easily performed. Further, since the road network data 2b for route search is provided separately from the display data, there is an effect that the road network data 2b can be read out at high speed. Note that the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, when a rewritable DVD-RAM is used instead of the storage medium 2, only the road network data corresponding to the section to be updated is received from the external information center by communication, and the section data of the DVD-RAM is updated. In addition, the amount of data handled in these communication processes is reduced, and the communication time and the associated communication cost can be reduced.

[0023]

As described above, according to the present invention, the road network data for route search and the drawing data to be drawn on the display screen are separately stored, and the plurality of road network data having a substantially uniform data amount are stored. Since the area is divided into areas, the road network data for route search can be read at high speed, and the route search can be accelerated if necessary.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a vehicle-mounted navigation device according to the present invention.

FIG. 2 is a diagram showing an outline of map drawing data of the present invention.

FIG. 3 is a diagram showing an outline of road network data of the present invention.

FIG. 4 is a diagram showing a hierarchical structure of road network data of the present invention.

FIG. 5 is a diagram showing a configuration of road network data of the present invention.

FIG. 6 is a diagram showing data constituting a road unit.

FIG. 7 is a diagram showing conventional map data divided into equal areas.

[Explanation of symbols]

 2a: Map drawing data for drawing a map image 2b: Road network data for route search

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09B 29/10 G06F 15/62 335

Claims (3)

[Claims] 1. A method of storing road network data for route search including link string data relating to a link string in which one or more links are minimum units representing a road shape and drawing data to be drawn on a display screen are separately stored. An on-vehicle navigation device, comprising: a map data storage unit configured to perform a route search based on the road network data stored in the map data storage unit; An on-vehicle navigation device, wherein the navigation device is divided into a plurality of regions having substantially uniform amounts. 2. The in-vehicle navigation device according to claim 1, wherein the road network data for route search includes an area having all of predetermined expressway data. 3. The in-vehicle navigation device according to claim 1, wherein the road search road network data is updated in units of the area.