JPH10103993A - Map-data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit map data to a vehicle at an accurate timing even when a data transmission rate is low by a method wherein the map data at the front in the advance direction of the vehicle is acquired in advance and retained by an on-vehicle apparatus. SOLUTION: A radio telephone 2f is connected to a control part 3b at an on-vehicle apparatus 2 through a modem 2e, and map data is exchanged between the on-vehicle apparatus and a center apparatus 1. The control part 3b transits data on the present position of a vehicle and on its advance direction to the center apparatus 1 and requests map data. The center apparatus 1 retrieves map data on an estimated position at the front in the advance direction of the vehicle and transmits the retrieved map data to the vehicle. In the on-vehicle apparatus 2, the transmitted map data is stored temporarily in a memory 3c for prefetch, and it is then displayed on a display when the vehicle is going out of position on a map which is displayed at present. In this manner, the map data, on the advance direction, which is acquired in advance so as to be stored can be displayed immediately when the vehicle enters its region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an in-vehicle device.
The present invention relates to a system for acquiring map data and the like around a vehicle from a ground system such as a base station or a fixed station.

[0002]

2. Description of the Related Art When a map around a vehicle is displayed by a vehicle-mounted navigation device, map data stored in a storage medium such as a CD-ROM is read and displayed. Although the storage medium has a relatively large capacity, the stored contents cannot be easily rewritten. Therefore, when there is a newly opened road or a newly applied traffic regulation, it is impossible to display a map that reflects these. Even if an attempt is made to replace the storage medium with a new storage medium, the work of revising the map data is not performed frequently, so that it is impossible to always obtain the latest map data.

Therefore, recently, some systems have been proposed in which a storage medium such as a CD-ROM is not provided in a vehicle, and the latest map data is received from a base station or a fixed station (particularly). JP-A-4-266228, JP-A-4-261576, JP-A-8-222
No. 46, etc.).

[0004]

In the above-mentioned existing system, a two-way beacon radio line, a car telephone line, a portable telephone line, and the like are usually used to transmit map data to a vehicle. Since these lines have a low data transmission rate,
It takes time to transfer the map data required to display on the screen.

[0005] However, since the vehicle moves, when the transfer of the map data is completed, a situation may occur in which the vehicle is already at the end of the range of the map data or has deviated. There is no problem if a sufficiently wide range of map data can be transferred. However, as described above, a wide range of map data cannot be transmitted at a time in consideration of the data transmission speed of the line and the transmission cost.

Accordingly, an object of the present invention is to realize a map data transmission system capable of transmitting map data to a vehicle at an accurate timing even if the data transmission speed is low.

[0007]

According to the present invention, there is provided a map data transmission system, comprising: a positioning means for measuring a current position and a traveling direction of a vehicle in an on-vehicle device; and a current position and travel of the vehicle obtained by the positioning means. Communication means for transmitting data with the direction; storage means for temporarily storing map data sent from the ground system; and display means for displaying map data. Receiving the data of the current position and the traveling direction of the vehicle based on the data, a search unit for searching the map data ahead of the traveling direction based on the data, and a transmitting unit for transmitting the map data searched by the searching unit are provided. (Claim 1).

[0008] According to the above configuration, the vehicle-mounted device can acquire and store the map data ahead of the traveling direction of the vehicle in advance, so that when the vehicle enters the adjacent map area,
The map can be displayed immediately. The communication means, in addition to the data of the current position and the traveling direction of the vehicle,
The speed data of the vehicle may be transmitted, and the search means may change the information amount of the map data to be transmitted based on the speed data (claim 2).

According to a third aspect of the present invention, there is provided a map data transmission system according to the vehicle-mounted device, wherein the data of the traveling direction of the vehicle is replaced with the data of the traveling direction of the vehicle.
A system that transmits a route to a set destination and, when receiving data on the current position of the vehicle and the route in the ground system, searches for map data along the route based on the data and transmits the map data. is there. As described above, if the route data is transmitted, a more accurate map along the route can be searched and displayed on the vehicle-mounted device than the case where the data on the traveling direction of the vehicle is transmitted.

The communication means transmits vehicle speed data in addition to the current position and route data of the vehicle, and the search means determines the amount of map data to be transmitted based on the speed data. It may be changed (claim 4). In the case of claim 2 or claim 4, as the speed of the vehicle increases, the amount of map data to be transmitted can be reduced, so that the map data can be sent faster. At this time, it is possible to prevent a disadvantage that a map to be displayed is interrupted.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration example of a map data transmission system. The map data transmission system is roughly divided into a central center device 1 and an on-vehicle device 2. The in-vehicle device 2 includes a navigation device 3, a distance sensor 2a and a direction sensor 2b that respectively detect a moving amount and a direction change amount of the vehicle, a GPS receiver 2c, a display 2d, a modem 2e, and a wireless telephone 2f. In addition, the navigation device 3 is connected to remote control keys for manually controlling the navigation device, a voice output device for outputting route guidance for intersections by voice, and the like (both not shown).

The position detecting section 3a of the navigation device 3
Calculates the current position data of the vehicle at predetermined intervals by so-called self-contained navigation based on the vehicle movement amount data and the azimuth change amount data output from the sensors 2a and 2b. Note that the current position of the vehicle is detected by the position detecting unit 3.
GPS navigation may be applied in which a radio wave transmitted from a GPS satellite is received by the GPS receiver 2c connected to a and a position of the vehicle is detected based on a propagation delay time of the radio wave. Further, the current position of the vehicle obtained by the self-contained navigation may be corrected based on the current position of the vehicle obtained by the GPS navigation (see JP-A-63-247612).

The current position data of the vehicle detected by the position detecting section 3a is given to the control section 3b. The control unit 3b
It functions as a control center of the navigation device, and displays the vehicle position detected by the position detection section 3a on a display screen of a display 2d composed of a liquid crystal display element or the like together with a map sent from the central center device 1. A display controller 3e, a display memory 3d for storing map data to be displayed on the display 2d, and the central center device 1.
Is connected to a prefetch memory 3c for storing map data to be displayed next on the display 2d acquired from.

A wireless telephone 2f is connected to the control unit 3b through a modem 2e. This wireless telephone 2
f is for exchanging map data with the central center apparatus 1, and an automobile telephone, a mobile telephone, or the like can be used. The control unit 3b controls the central
It has a function of transmitting data representing the current position and traveling direction of the vehicle and data representing the initial state and requesting map data, and these requests are transmitted to the central center device 1 through the wireless telephone 2f.

The data of the traveling direction of the vehicle is, for example, data obtained by dividing 360 degrees in all directions into 16 directions. The data representing the initial state is data necessary when the power of the vehicle-mounted device 2 is turned on, since the storage in the display memory 3d is lost and a map near the current position cannot be displayed. Reference numeral 3 denotes a code indicating whether or not map data near the current position of the vehicle already exists. For example, when the map data near the current position is held, 1 is set, and when not, 0 is set.

If the display memory 3d is a non-volatile memory, the map data at the time when the power of the vehicle-mounted device 2 was previously turned off remains, so that the data representing the initial state is unnecessary.
The central center device 1 is installed in an organization that manages road traffic information and map data, and includes a traffic information data file 1a that holds real-time road traffic information such as traffic congestion information, traffic regulation information, and travel time information. , A map data file 1b holding map data, a search unit 1c for searching the file, a data amount changing unit 1d for changing the data amount of the searched map data, a modem 1e and a telephone terminal 1f.

The map data held in the map data file 1b needs to be in the same format as the map data generally used in the navigation device. For example, the map data file 1b divides a map (including a high-speed automobile national road, an automobile exclusive road, a general national road, a prefectural road, a city road of a designated city, and other living roads) into a mesh shape, and maps each map mesh unit. For example, data consisting of a combination of nodes corresponding to road intersections or bending points and links connecting the nodes and background data necessary for display are stored. Here, the "background necessary for display" refers to famous buildings, parks, seas, lakes and marshes, rivers, railways, place names, resorts, and the like.

The map mesh is further subdivided, and each unit is called a "block" here. When receiving the data of the current position and the traveling direction of the vehicle and the data indicating the initial state from the on-vehicle device 2, the search unit 1c searches the map data based on the data,
The transmission is performed using the telephone terminal 1f.

The search function of the search unit 1c will be specifically described with reference to FIG. FIG. 2 is a diagram showing a map mesh where vehicles exist and eight map meshes adjacent to the map mesh. Each map mesh is divided into nine blocks. The map mesh or block acquired by the search unit 1c is a map mesh or block located ahead in the traveling direction of the vehicle. For example, assuming that the vehicle is traveling in the northeast direction as shown in FIG. 2, the block specified by the upper right diagonal line in FIG. 2 is the acquisition target.

The validity of such an acquisition method will be examined.
For example, it is assumed that the vehicle-mounted device 2 acquires map data through a mobile phone and displays a map of an area of 500 m × 500 m on a display. The amount of map data displayed is 2
The communication speed of the mobile phone is 9600 bps. The time required to transfer one screen of map data is about 17 seconds. Assuming that the vehicle travels at a constant speed of 40 km / h, it takes about 22 seconds to move from the center of the map screen to one end.

Therefore, even if a request is made for map data of a map mesh where a vehicle is present, the vehicle is moving toward the edge of the screen by the time the map data is displayed. If the map data of the adjacent map mesh in the traveling direction of the vehicle is requested at that time, it takes another 17 seconds from the request to the display, so that the map display of the adjacent map mesh cannot be made in time. That is, the map to be displayed is interrupted.

Therefore, as described above, a map mesh or block ahead in the traveling direction of the vehicle is prefetched. This eliminates the inconvenience that the map to be displayed is interrupted. On the contrary, a display mode in which the position of the vehicle is fixed in the screen and the map is scrolled becomes possible. It is inconvenient to use if there is no display map near the current position of the vehicle immediately after the power of the navigation device 3 is turned on. At this time, since the code 0 representing the above-described initial state is sent, the search unit 1c acquires and transmits map data including the current location where the vehicle is located.

Hereinafter, after the power of the vehicle-mounted device 2 is turned on, data is transmitted from the vehicle-mounted device 2, the data is received by the central center device 1, and map data near the current position is searched. Is transmitted to the vehicle, and the in-vehicle device 2 describes a series of procedures for displaying the map data transmitted from the central center device 1 on the display 2d with reference to a flowchart (FIG. 3).

When the vehicle-mounted device 2 is started, first, the vehicle-mounted device 2
Transmits data of the current position and the traveling direction of the vehicle and a code 0 representing the initial state (step S1). Thereafter, the vehicle continues to run (step S2), and receives map data near the current position from the central center device 1 (step S3), and stores the data in the display memory 3d (step S2).
4) Display on the display 2d (Step S)
5).

Next, data is transmitted from the vehicle-mounted device 2 as the vehicle travels, the data is received by the central center device 1, and map data of a predicted position ahead of the traveling direction is searched. A series of procedures for transmitting the data to the vehicle and temporarily storing the map data sent from the central center device 1 in the prefetch memory 3c and then displaying the map data on the display 2d in the vehicle-mounted device 2 will be described with reference to a flowchart (FIG. 4). Will be explained.

The in-vehicle device 2 transmits the data of the current position and the traveling direction of the vehicle and the code 1 representing the initial state (step S7). Thereafter, the vehicle continues traveling (step S2), and when map data near the predicted position is received from the central center device 1 (step S3), the data is temporarily stored in the prefetch memory 3c (step S10). If the vehicle continues traveling (step S11) and confirms that the position of the vehicle is likely to deviate from the currently displayed map (step S12), the map data stored in the prefetch memory 3c is read and displayed. (Step S13). At the time this transfer is made,
Of the map memories stored in the display memory 3d,
The data on the opposite side of the traveling direction is discarded (Fig. 2
And the block indicated by x). Then, the map is displayed (step S14).

As described above, since the map data of the traveling direction of the vehicle is acquired and stored in advance, when the vehicle enters the map area of the adjacent map mesh, the map can be immediately displayed on the display 2d. Next, an embodiment in which the information amount of the map data to be transmitted is changed according to the speed of the vehicle will be described.

In this embodiment, the control unit 3b of the vehicle-mounted device 2
Transmits the data of the current position and the traveling direction of the vehicle, and also transmits the speed data of the vehicle. It is preferable that the speed data is a speed averaged over a certain period of time in the past, rather than instantaneous data. In the central center device 1, the map data is ranked and stored in several stages so that the map data amount can be changed. For example, when sending the most detailed map data,
Send background data of all ranks together with combination data of all nodes and links. When sending simple map data, the node data, link data, and background data of the lower rank are omitted and transmitted. The ranking may be given based on whether there is no problem even if the display is omitted (whether the importance as the map data is low).

Data amount changing section 1d of central center device 1
When it is determined based on the received vehicle speed data that the speed of the vehicle is so high that all the map data cannot be transferred while passing over a distance of one screen, the map data amount is reduced and sent. In this manner, when the vehicle speed is high, the time for sending the map data can be shortened, so that the inconvenience of the map to be displayed being interrupted can be prevented.

Next, an embodiment in which recommended route information is transmitted from the vehicle-mounted device 2 instead of transmitting data on the traveling direction of the vehicle will be described. In this embodiment, the navigation device 3 of the in-vehicle device 2 includes a route acquisition unit 3f that acquires a recommended route from the central center device 1 (see the broken line in FIG. 1).
When various calculation conditions such as a destination are input by the user, the route acquisition unit 3f sends the input destination data and the like to the central center device 1 through the wireless telephone 2f, and sends the destination data from the central center device 1 to the destination. A route to be obtained is obtained (such a method of obtaining a route is well known.
190794).

However, the route acquisition method is not limited to the above example. For example, the navigation device 3 prepares a route calculation map memory, and
The recommended route between the current position and the destination detected in a may be calculated using the Dijkstra method or the potential method. Alternatively, the recommended route may be calculated by a personal computer using the route calculation software and stored in a memory card, and the memory card may be uploaded to the navigation device 3 to acquire the recommended route.

The control unit 3b transmits data on the current position of the vehicle and the recommended route. Search unit 1c of central center device 1
When receiving the data of the current position of the vehicle and the recommended route from the vehicle-mounted device 2, the device searches for the map data based on the data. For example, as shown in FIG. 5, the recommended route is sequentially followed, and the recommended route is the range of the map data currently held by the vehicle-mounted device 2 (whether or not the recommended route is held is determined from the past map data transmission history. When it deviates from the recommended route, the map data of blocks around the deviated recommended route (see hatched blocks in FIG. 5) is specified.

As described above, if the recommended route data is transmitted, even if the recommended route has a turn and is different from the current traveling direction of the vehicle, a map along the recommended route is searched. It can be displayed on the display 2d of the vehicle-mounted device 2. In this embodiment, the information amount of the map data to be transmitted may be changed according to the speed of the vehicle.

Although the embodiment has been described above, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the invention described in the claims. It is possible.

[0035]

As described above, according to the map data transmission system according to the first aspect, the on-vehicle device can acquire and store the map data ahead of the traveling direction of the vehicle from the ground system in advance. When a vehicle enters the adjacent map area,
The map can be displayed immediately. Therefore, it is possible to prevent the inconvenience that the map to be displayed is interrupted.

According to the map data transmission system of the third aspect, since the route data is transmitted, an accurate map along the route can be searched and displayed on the vehicle-mounted device.
This is particularly effective when the traveling direction of the vehicle is different from the route. According to the map data transmission system of the second or fourth aspect, when the vehicle speed is high, the time for transmitting the map data can be shortened, so that the inconvenience that the map to be displayed is interrupted can be prevented. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration example of a map data transmission system.

FIG. 2 is a diagram showing a map mesh where a vehicle exists and eight map meshes adjacent to the map mesh;

FIG. 3 is a diagram showing a state in which the power of the vehicle-mounted device 2 is turned on, data is transmitted from the vehicle-mounted device 2, the central center device 1 receives the data, searches for map data near the current position, The vehicle data is transmitted to the vehicle, and the in-vehicle device 2 displays the map data transmitted from the central center device 1 on the display 2.
9 is a flowchart showing a series of procedures to be displayed on d.

FIG. 4 transmits data from the in-vehicle device 2 as the vehicle travels, receives the data in the central center device 1, searches for map data of a predicted position ahead of the traveling direction,
The searched map data is transmitted to the vehicle, and the in-vehicle device 2
After temporarily storing the map data sent from the central center apparatus 1 in the prefetch memory 3c, the display 2
9 is a flowchart showing a series of procedures to be displayed on d.

FIG. 5 is a diagram showing a map mesh in which a vehicle exists, eight map meshes adjacent to the periphery thereof, and a recommended route;

[Explanation of symbols]

 Reference Signs List 1 Central center device 2 In-vehicle device 2a Distance sensor 2b direction sensor, 2c GPS receiver, 2d display, 2e modem 2f wireless telephone 3 Navigation device 3a Position detector 3b controller 3c Prefetch memory 3d display memory 3e display controller

Continued on the front page (51) Int.Cl. ⁶ Identification code FI H04M 11/08 H04M 11/08

Claims (4)

[Claims] An on-vehicle device comprising: positioning means for measuring a current position and a traveling direction of a vehicle; communication means for transmitting data on a current position and a traveling direction of the vehicle obtained by the positioning means; Storage means for temporarily storing the map data sent from the vehicle, and display means for displaying the map data. In the terrestrial system, if data of the current position and the traveling direction of the vehicle is received from the vehicle through the communication means, A map data transmission system comprising: a search unit that searches for map data ahead in the traveling direction based on the data; and a transmission unit that transmits the map data searched by the search unit. 2. The communication means transmits vehicle speed data in addition to data on a current position and a traveling direction of the vehicle, and the search means transmits map data transmitted based on the speed data. 2. The map data transmission system according to claim 1, wherein the information amount is changed. 3. A vehicle-mounted device, comprising: positioning means for measuring a current position of a vehicle; route obtaining means for obtaining a route to a set destination; data of a current position of the vehicle obtained by the positioning means; A communication unit for transmitting the route data obtained by the route acquisition unit; a storage unit for temporarily storing map data sent from the ground system; and a display unit for displaying the map data. Receiving the data of the current position and the route of the vehicle from the communication device through the communication device, searching for map data along the route based on the data, and transmitting the map data searched by the search device. And a means for transmitting map data. 4. The communication means transmits vehicle speed data in addition to the current position and route data of the vehicle, and the search means transmits map data information based on the speed data. The map data transmission system according to claim 3, wherein the amount is changed.