JP2005025037A - Map data distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for improving the positional accuracy of a communication type navigation system by eliminating an error resulting from delay in data transmission. <P>SOLUTION: A center receives the information on movement of a mobile terminal from the mobile terminal immediately at a map request; estimates a delay time taken until the mobile terminal receives a map data in accordance with the request after transmitting the map request; predicts the presence position at the time when the mobile terminal will receive the map data, from the estimated delay time and the movement information of the mobile terminal; produces the map data containing the information as to the predicted presence position; and transmits the produced map data to the mobile terminal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a map data distribution system suitable for use in a navigation system using a network.
[0002]
[Prior art]
Car navigation devices (car navigation systems) mounted on vehicles are widely used. A typical car navigation system has a recording medium (CD-ROM, DVD-ROM, hard disk, etc.) that stores map data and POI (Point Of Interest) data, and obtains position information from GPS (Global Positioning System). In addition, it has a function of displaying the current position and its peripheral information superimposed on a map, and displaying route guidance to a destination.
[0003]
With the progress of communication technology, a communication type navigation system using a network has recently attracted attention. The communication type navigation system realizes a navigation function by data communication between the in-vehicle terminal and the center. For example, Patent Documents 1 and 2 propose a system in which when the in-vehicle terminal transmits position information to the center, map data and route data are generated on the center side and distributed to the in-vehicle terminal.
[0004]
[Patent Document 1]
JP-A-10-260048 [Patent Document 2]
Japanese Patent Laid-Open No. 2003-65785
[Problems to be solved by the invention]
When considering use in a vehicle moving at high speed, in such a communication type navigation system, it is ideal that data transmission between the in-vehicle terminal and the center is executed in real time.
[0006]
However, a problem of communication delay always occurs in data transmission in a network. For example, in an IP (Internet Protocol) network such as the Internet, a packet arrival delay occurs in the range of several tens of milliseconds to several seconds due to various factors such as transmission path quality and network device performance. Further, although depending on the communication performance and data capacity of the in-vehicle terminal, a time lag occurs between the time when the in-vehicle terminal starts to receive map data and the time when the map data is displayed.
[0007]
A vehicle traveling at 60 km / h moves 16.7 m per second. Therefore, if a communication delay of 1 second occurs when the uplink and downlink of the communication are combined, an error of 16.7 m occurs from when the in-vehicle terminal transmits the position information to when the map data is received and displayed. It will be. Needless to say, this error is fatal for car navigation systems.
[0008]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique for eliminating an error caused by a delay in data transmission and improving the positional accuracy of a communication navigation system. It is in.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the map data distribution system of the present invention distributes map data to mobile terminals by the following means or processing. The following means or processes relating to the map data distribution process are specifically realized by reading and executing a program in a computer system.
[0010]
The map data distribution system receives the movement information of the mobile terminal together with the map request from the mobile terminal by the request receiving means.
[0011]
Here, the exercise information is information related to “movement” of the mobile terminal. The exercise information may include at least position information indicating the current position of the mobile terminal, direction information indicating the moving direction of the mobile terminal, and speed information indicating the moving speed of the mobile terminal. Further, it is more preferable that acceleration information indicating the acceleration of the mobile terminal, tilt information indicating the tilt angle of the mobile terminal, and the like are included.
[0012]
When the map data distribution system receives a map request from the mobile terminal, the delay estimation means estimates a delay time required from the mobile terminal transmitting the map request to receiving the map data corresponding to the request.
[0013]
There are various factors that cause such a delay time. For example, a communication delay between the map data distribution system and the mobile terminal, a time required for transmitting map data to the mobile terminal, a calculation time in the map data distribution system, and the like are assumed. Which of these delay factors affects the delay time most depends on the system configuration, terminal configuration, network configuration, and the like. Therefore, the delay estimation means may consider all delay factors, but may consider only one or several delay factors that have a large influence on the delay time.
[0014]
When considering communication delay, it is preferable to provide communication delay measuring means for measuring communication delay. Although the degree of delay varies depending on the quality of the transmission path interposed between the system and the mobile terminal, the delay time can be reduced by measuring the actual communication delay periodically or as required by the communication delay measurement means. The estimation accuracy can be improved.
[0015]
The communication delay measuring means preferably measures the communication delay from the difference between the transmission time and the reception time by, for example, transmitting a delay measurement message to the mobile terminal and receiving the confirmation response. Thereby, it is possible to actually measure both upstream and downstream communication delays. Alternatively, it is also preferable that the communication delay measuring unit synchronizes the time of the map data distribution system and the mobile terminal. Thereby, it is possible to easily actually measure the uplink or downlink communication delay from the difference between the transmission time included in the data and the reception time when the data is received.
[0016]
When the map data distribution system estimates the delay time, the position prediction means predicts the location at the time when the mobile terminal will receive the map data from the delay time and the motion information of the mobile terminal.
[0017]
Typically, based on the motion information, the distance and direction in which the mobile terminal moves during the delay time is calculated, and the presence position is obtained by adding the displacement to the current position of the mobile terminal.
[0018]
Alternatively, when the planned movement route of the mobile terminal is known, the presence position may be predicted based on the planned movement route. As a result, information on whether or not the mobile terminal makes a turn can be taken into account, and the reliability of the predicted location can be improved.
[0019]
Next, the map data distribution system generates map data including information on the predicted location by the map generation means. For example, it is preferable to generate map data in which an icon or mark indicating an existing position is drawn on the map.
[0020]
And a map data delivery system transmits the map data to a mobile terminal by a map transmission means.
[0021]
As described above, according to the present invention, the delay time of data transmission with the mobile terminal is estimated, and map data in which an error caused by the delay is corrected in advance is generated and distributed. The accuracy can be improved.
[0022]
In addition, this invention can be grasped | ascertained as a map data delivery system or a communication-type navigation system which has at least one part of the said means. Moreover, this invention can also be grasped | ascertained as the map data delivery method containing at least one part of the said process, or the program for implement | achieving this method. Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.
[0023]
For example, a map data distribution system as one aspect of the present invention includes a request receiving unit that receives, from a mobile terminal, motion information of the mobile terminal together with a map request, and responds to the request after the mobile terminal transmits the map request. Based on the delay estimation means for estimating the delay time required to receive the map data, and the estimated delay time and the motion information of the mobile terminal, the location at which the mobile terminal will receive the map data is predicted. It is preferable to include a position predicting unit, a map generating unit that generates map data including information on the predicted location, and a map transmitting unit that transmits the generated map data to the mobile terminal.
[0024]
Further, in the map data distribution method as one aspect of the present invention, the computer system receives from the mobile terminal the motion information of the mobile terminal together with the map request, and the mobile terminal transmits the map request to the request. Predicting the location at which the mobile terminal will receive the map data from the step of estimating the delay time required to receive the corresponding map data, and the estimated delay time and the motion information of the mobile terminal It is preferable to execute a step, a step of generating map data including information on the predicted location, and a step of transmitting the generated map data to the mobile terminal.
[0025]
In addition, the map data distribution program as one aspect of the present invention includes a process for receiving, from a mobile terminal, movement information of the mobile terminal together with a map request from the mobile terminal, and a request after the mobile terminal transmits the map request. Predicting the location at which the mobile terminal will receive the map data from the process of estimating the delay time required to receive the corresponding map data, and the estimated delay time and the movement information of the mobile terminal It is preferable to execute a process, a process of generating map data including information on the predicted location, and a process of transmitting the generated map data to the mobile terminal.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings.
[0027]
FIG. 1 is a block diagram showing the overall configuration of a communication navigation system. The communication navigation system includes a map data distribution system 1 and a mobile terminal 2 that can communicate with each other via a wide area network 3 such as the Internet.
[0028]
The mobile terminal 2 is an in-vehicle terminal installed in a vehicle 20 that is a moving body. The mobile terminal 2 includes a display device 21 and a communication IF 22. The display device 21 is a display means for displaying map data and the like, and the communication IF 22 is a communication means for realizing wireless communication using the base station 4. The communication IF 22 can use a communication system such as a mobile phone, DSRC (Dedicated Short Range Communication), and wireless LAN (Local Area Network).
[0029]
In addition, the mobile terminal 2 has destination setting means for allowing the user to input a destination. The user can set the destination by inputting the name, address, telephone number, etc. of the destination, or specifying the position on the map displayed on the display device 21. At this time, the mobile terminal 2 may access the map data distribution system 1 as necessary to download a destination setting user interface and map data.
[0030]
The mobile terminal 2 is connected to various sensors 23 in the vehicle 20. The sensor 23 is a detection means for acquiring movement information of the mobile terminal 2 (that is, the vehicle 20), and includes a GPS, a vehicle speed sensor, a gyro (direction sensor), a G sensor, an inclination angle sensor, and the like. The mobile terminal 2 receives the current position information (latitude, longitude, altitude) from the GPS, the moving speed from the vehicle speed sensor, the moving direction from the gyroscope, the acceleration from the G sensor, and the inclination of the vehicle 20 from the inclination angle sensor. Get each corner.
[0031]
Thus, the mobile terminal 2 has a simple configuration that only has an exercise information acquisition function, a communication function, a display function, a destination setting function, and the like. Other car navigation functions (such as a route search function and a map data generation function) are performed by the map data distribution system 1. That is, the mobile terminal 2 realizes a function as a car navigation system in cooperation with the map data distribution system 1.
[0032]
In the present embodiment, an in-vehicle terminal is taken as an example of the mobile terminal 2, but the form of the mobile terminal 2 is not limited to this, and a portable mobile phone such as a mobile phone, a mobile personal computer, an information portable terminal (PDA), etc. A terminal is also included.
[0033]
The map data distribution system 1 is generally composed of a center 10 and a map DB (database) 11. The various functions of the map data distribution system 1 are as follows. In a general-purpose computer system including a CPU (Central Processing Unit), a memory, a hard disk, a communication IF (interface), etc. as basic hardware, a program stored in the hard disk is stored in the CPU. It is realized by being read and executed. The center 10 and the map DB 11 can be configured by a single computer, or can be configured by a plurality of computers connected by a network.
[0034]
The map DB 11 is map information storage means in which map information (map data, POI data, etc.) necessary for route search and map data generation is stored. In the communication type navigation system of the present embodiment, since map information is held on the center side, maintenance such as change / update of map information is easy, and the latest information is always updated without changing the configuration of the mobile terminal 2. There is an advantage that map data can be provided.
[0035]
Next, a specific processing flow of the map data distribution system 1 and the mobile terminal 2 will be described with reference to FIG. FIG. 2 is a sequence diagram showing a flow of processing of the communication navigation system according to the present embodiment.
[0036]
(1) The center 10 transmits a delay measurement message to the mobile terminal 2 in order to measure a communication delay between the map data distribution system 1 and the mobile terminal 2. For example, as shown in FIG. 3, the delay measurement message includes a “delay measurement label” for identifying the delay measurement message and a “center time stamp” indicating the message transmission time.
[0037]
(2) Upon receiving the delay measurement message, the mobile terminal 2 immediately returns a delay measurement message ACK that is a confirmation response. For example, as shown in FIG. 4A, the delay measurement message ACK is a “delay measurement ACK label” for identifying the delay measurement message ACK, and a “center time stamp” indicating the message transmission time of the center 10. Consists of. As the “center time stamp”, the received delay measurement message is used. Alternatively, as illustrated in FIG. 4B, a delay measurement message ACK may be obtained by adding an identifier “ACK” indicating an acknowledgment to the received delay measurement message.
[0038]
When the center 10 receives the delay measurement message ACK, the center 10 calculates a communication delay by taking a difference between the reception time and the “center time stamp” included in the ACK. Note that the measurement of the communication delays (1) and (2) may be performed periodically at predetermined time intervals, or may be performed as necessary when data is transmitted to and received from the mobile terminal 2.
[0039]
(3) The mobile terminal 2 transmits a map request to the center 10. The map request is a message for requesting the center 10 to distribute map data. At this time, the mobile terminal 2 transmits exercise information and destination / relay point information together with a map request. In the present embodiment, the movement information includes “current position information” of the mobile terminal 2, “azimuth information” indicating the movement direction of the mobile terminal 2, “speed information” indicating the movement speed of the mobile terminal 2, and acceleration of the mobile terminal 2. And “inclination information” indicating the inclination angle of the mobile terminal 2 are included. This exercise information is used for position prediction processing described later. On the other hand, the destination / relay point information is information that is sent to the center 10 when destination setting is performed in the mobile terminal 2, and is not essential information.
[0040]
(4) Upon receiving a map request or the like from the mobile terminal 2, the center 10 checks whether destination / relay point information is included, and if included, performs a route search process. Specifically, the center 10 extracts the latitude / longitude of each of the “current location”, “relay location”, and “destination” from the motion information and the destination / relay point information, and refers to road information and the like in the map DB 11. Determine the optimal route from your current location to your destination. The planned movement route of the mobile terminal 2 obtained here is stored in a memory or a hard disk.
[0041]
(5) (6) Subsequently, the center 10 executes a delay estimation process and a position prediction process. These processes will be described with reference to the flowchart of FIG.
[0042]
Step S1 in FIG. 5 is the communication delay measurement process described above.
[0043]
Next, the center 10 calculates the transmission time of the map data (step S2). Here, the theoretical transmission time when it is assumed that no communication delay occurs is calculated from the capacity of the map data and the communication speed. Note that map data is not yet generated at this point, and therefore the average capacity or the expected capacity of the map data is used for calculating the transmission time.
[0044]
Then, the center 10 sums the communication delay calculated in step S1 and the transmission time calculated in step S2 (step S3). This total time includes a communication delay during the arrival of the map request from the mobile terminal 2 to the center 10, a communication delay during the arrival of the map data from the center 10 to the mobile terminal 2, and the mobile terminal 2 starts receiving the map data. Transmission time from completion to completion. In the present embodiment, the total time obtained in this way is set as a delay time required from when the mobile terminal 2 transmits a map request until the map data corresponding to the request is received.
[0045]
Next, the center 10 predicts the location at the time when the mobile terminal 2 will receive the map data from the delay time and the motion information of the mobile terminal 2. In the present embodiment, the content of the position prediction process is switched depending on whether or not the mobile terminal 2 has set a destination (step S4).
[0046]
If the destination is set, the planned movement route of the mobile terminal 2 is known, and the process proceeds to step S5. The center 10 substitutes the exercise information into the following equation to calculate the distance that the mobile terminal 2 moves during the delay time.
Y = VT + (1/2) AT ²
V: Speed of mobile terminal 2 (m / s)
A: Acceleration of mobile terminal 2 (m / s ² )
T: Delay time (s)
Y: Estimated travel distance of mobile terminal (m)
[0047]
Then, a point advanced by the distance Y along the planned movement route from the current position of the mobile terminal 2 is set as the predicted presence position of the mobile terminal 2.
[0048]
On the other hand, if the destination is not set, the mobile terminal 2 does not know the planned travel route, so the process proceeds to step S6. The center 10 calculates the distance Y in the same manner as in step S5, and sets the point advanced from the current position of the mobile terminal 2 by the distance Y in the moving direction as the predicted presence position of the mobile terminal 2.
[0049]
The existence position predicted here is transferred to the map data generation process.
[0050]
(7) The center 10 generates map data including information related to the predicted location. That is, the center 10 extracts the map / POI information around the predicted location from the map DB 11, draws an icon or mark indicating the location (vehicle position) on the map, and if there is a planned travel route, The route is also drawn. It is also preferable to draw POI information, traffic information, etc. in an overlapping manner.
[0051]
(8) Then, the center 10 transmits the generated map data to the mobile terminal 2.
[0052]
(9) When receiving the map data from the center 10, the mobile terminal 2 displays it on the display device 21. As a result, the current position and moving route of the vehicle are presented to the driver, and a car navigation function is realized.
[0053]
The mobile terminal 2 and the center 10 sequentially update the map display by repeating the above sequence. When there is no change in the destination / relay point, the route search process (4) can be omitted as shown in the second half of FIG.
[0054]
According to the system of the present embodiment described above, the delay time of data transmission with the mobile terminal 2 is estimated, and map data in which an error caused by the delay is corrected in advance is generated and distributed. The position accuracy of the system can be improved.
[0055]
Although the degree of delay varies depending on the quality of the transmission path interposed between the system and the mobile terminal 2, the actual communication delay is measured periodically or as necessary in this embodiment. The estimation accuracy of the delay time can be improved.
[0056]
Furthermore, by performing the position prediction based on the planned movement route of the mobile terminal 2, it is possible to consider information such as whether or not the mobile terminal 2 is turning at an intersection, so that the reliability of the predicted location can be improved.
[0057]
In addition, the said structure is only what illustrated one Embodiment of this invention. The scope of the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the technical idea.
[0058]
For example, in the above-described embodiment, two delay factors of communication delay and transmission time are considered as the delay time. However, only one of them may be considered, or another delay factor may be considered. Since it suffices that the error due to the delay time falls within an error range acceptable by the car navigation system, it is not necessary to strictly consider all delay factors.
[0059]
In the above embodiment, the communication delay is measured by exchanging the delay measurement message and its ACK. However, the communication delay can be easily measured by synchronizing the time of the mobile terminal 2 and the center 10. . In this case, when the center 10 receives a map request, the center 10 can calculate a one-way communication delay from the difference between the map request transmission time of the mobile terminal 2 and the reception time at the center 10.
[0060]
【The invention's effect】
As described above, according to the present invention, a delay time of data transmission with a mobile terminal is estimated, and map data in which an error caused by the delay is corrected in advance is generated and distributed. The position accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a communication navigation system.
FIG. 2 is a sequence diagram showing a processing flow of the communication navigation system.
FIG. 3 is a diagram illustrating a configuration example of a delay measurement message.
FIG. 4 is a diagram illustrating a configuration example of a delay measurement message ACK.
FIG. 5 is a flowchart showing a flow of delay estimation processing and position prediction processing.
[Explanation of symbols]
1 Map data distribution system 2 Mobile terminal 3 Wide area network 4 Base station 10 Center 11 Map DB
20 Vehicle 21 Display device 22 Communication IF
23 Sensor

Claims (7)

A request receiving means for receiving movement information of the mobile terminal together with a map request from the mobile terminal;
A delay estimation means for estimating a delay time required from when the mobile terminal transmits a map request to receiving map data corresponding to the request;
A position predicting means for predicting an existing position at a time at which the mobile terminal will receive the map data from the estimated delay time and the motion information of the mobile terminal;
Map generation means for generating map data including information on the predicted location,
Map transmission means for transmitting the generated map data to the mobile terminal;
A map data distribution system. The map data distribution system according to claim 1, wherein when the planned movement route of the mobile terminal is known, the position prediction unit predicts the presence position based on the planned movement route. The map data distribution system according to claim 1, wherein the delay estimation unit estimates the delay time in consideration of a communication delay between the map data distribution system and the mobile terminal. The map data distribution system according to claim 3, further comprising communication delay measuring means for measuring a communication delay between the map data distribution system and the mobile terminal. 5. The map data distribution system according to claim 1, wherein the delay estimation unit estimates the delay time in consideration of a time required for transmission of map data to a mobile terminal. Computer system
Receiving movement information of the mobile terminal together with the map request from the mobile terminal;
Estimating a delay time required from when the mobile terminal transmits a map request to receiving map data corresponding to the request;
Predicting a location at a time at which the mobile terminal will receive map data from the estimated delay time and the mobile terminal's motion information;
Generating map data including information about the predicted location;
Sending the generated map data to the mobile terminal;
Map data distribution method to execute. Computer system,
A process of receiving movement information of the mobile terminal together with a map request from the mobile terminal;
A process of estimating a delay time required from when the mobile terminal transmits a map request to receiving map data corresponding to the request;
From the estimated delay time and the movement information of the mobile terminal, a process of predicting the location at which the mobile terminal will receive map data;
A process of generating map data including information on the predicted location,
A process of transmitting the generated map data to the mobile terminal;
Map data distribution program to execute.

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