JP2005043180A - Map display method and navigation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce computation load on a navigation system and acquire and display maps and guidance route information from an external device at an appropriate timing according to a vehicle speed. <P>SOLUTION: The navigation system NAV previously acquires both the next map information requisition time and an identifier of map information from a server SEV, and transmits the map identifier and the location of one's own vehicle to the server when present time reaches the map information requisition time. The server downloads map information of the map identifier to the navigation system, computes a travel speed on the basis of the location of one's own vehicle, determines the next map information requisition time on the basis of the travel speed, and transmits the map information requisition time and an identifier of the next map information to the navigation system. The navigation system displays maps on a display screen on the basis of the map information acquired from the server, acquires the map information requisition time and the identifier of the next map information, and repeats the above-mentioned operations. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a map display method and a navigation device, and more particularly, a navigation device that sequentially obtains and displays map information and guidance route information around a vehicle position from an external device through communication according to the traveling of the vehicle and a map thereof. It relates to the display method.
[0002]
[Prior art]
A navigation device that provides driving guidance for a vehicle so that a driver can easily reach a desired destination by detecting the position of the vehicle and detecting the position around the vehicle position from a map recording medium (for example, a CD-ROM or a DVD disk). Map data is read out, a map image is drawn on the display screen, and a vehicle position mark is drawn at a predetermined location on the map image. As the vehicle position changes due to the movement of the vehicle, the vehicle position mark is fixed at a predetermined position on the screen and the map is scrolled so that the map information around the vehicle position can always be seen at a glance. Further, the navigation device has a route guidance function for searching for a guidance route from the departure point to the destination and displaying the guidance route on a map.
[0003]
Since such a navigation device uses a CD-ROM or DVD-ROM as a map database (map storage medium), it requires a CD-ROM drive or DVD drive for reading map information from these map storage media. This is a factor of high cost and large equipment. Further, since a fixed recording medium such as a CD-ROM or DVD-ROM is used as the map database (map storage medium), there is a problem that it is difficult to always reflect the latest data.
From the above, a communication navigation system that does not require a map recording medium, acquires necessary map information from an external server device by communication in a timely manner, and displays a map and a guidance route around the vehicle is being put into practical use.
[0004]
FIG. 5 is an explanatory diagram of a conventional communication navigation (conventional technology 1). The navigation device sends a departure point _PST and a destination _PDT to the server device by communication, and receives map information MP0 and guidance route information around the vehicle. Obtained from the server, the map and the guide route are displayed using the map information MP0 and the guide route information. The communication navigation device monitors the position of the vehicle, and if the next map information MP1 and guidance route information are required by traveling, the information is requested from the server device, and thereafter the map and guidance route to the destination are displayed in the same manner. To do.
[0005]
As prior art 2, the map download means in the mobile terminal calculates the estimated movement position after a predetermined time based on the moving direction and moving speed, and the estimated movement position is not in the map information stored in the memory. At the same time, there has also been proposed a communication navigation system in which map information around the estimated movement position is quickly downloaded from the center system and stored in a memory so that the position display is not interrupted during map download (Patent Document). 1).
Further, as the prior art 3, there is an off-board navigation that does not have map data in an in-vehicle device and pre-reads and downloads a map necessary for navigation via a wireless network before it is necessary. In this off-board navigation, generally, the download time (first method) or position (second method) is calculated based on the route / predicted movement distance, and a map download is requested at these times or positions. Is.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2002-71376
[Problems to be solved by the invention]
In the prior art 1, the vehicle position is monitored on the navigation side, the vehicle is detected at the position where the next map information is requested, and the external device is requested each time. There is a growing problem.
In the prior art 2, the estimated movement position after a predetermined time is calculated on the navigation side, and when the estimated movement position is not in the map information stored in the memory, the map information around the estimated movement position is requested to the center system. As a result, there is a problem that the load on the navigation device increases as in the case of the prior art 1.
[0007]
The first method of Prior Art 3 predicts the time to download the necessary map information from the route / predicted travel distance. However, the calculation load becomes large, and it greatly depends on road conditions, traveling speed, accident conditions, etc. There is a problem that the predicted time is likely to change. In the second method of Prior Art 3, the vehicle position is determined and the next required map download is requested, but it can be executed at an appropriate timing depending on road conditions, traveling speed, accident conditions, etc. Not exclusively. In addition, determining the position of the vehicle and calculating the timing at which the next map is required requires a large amount of calculation as described in Related Art 1, and places a heavy burden on the in-vehicle device. Off-board navigation often uses a “light CPU” and it is not preferable to increase the amount of calculation. In addition, in the method of taking in the map on the route in advance, there is a problem that the memory of the in-vehicle device is limited, and in the case of a route change, useless communication occurs.
From the above, the object of the present invention is to reduce the calculation load on the navigation device side, and to acquire and display maps and guide route information at an appropriate timing considering road conditions, travel speeds, accident conditions, etc. It is.
[0008]
[Means for Solving the Problems]
A first aspect of the present invention is a map display method for a navigation device that sequentially obtains and displays map information around the vehicle position from an external device in accordance with the traveling of the vehicle. The map display method of this navigation device includes the step of acquiring the time for requesting the next map information and the identifier of the map information from an external device in advance, measuring the vehicle position, and the current time as the map information request time. A step of monitoring whether the current time is the map information request time, a step of transmitting the map identifier and the vehicle position to an external device, a map information of the map identifier is acquired from the external device, and a display device And acquiring and storing the next map information request time and an identifier of the map information determined in consideration of the traveling speed calculated based on the vehicle position from the external device, Thereafter, there is a step of repeating the above operation using the map information request time and the identifier of the map information.
[0009]
The second aspect of the present invention is a navigation device that sequentially obtains and displays map information around the vehicle position from an external device according to the traveling of the vehicle. The navigation device includes a display unit that sequentially displays map information around the vehicle position according to the travel of the vehicle, a unit that obtains a time for requesting the next map information and an identifier of the map information in advance from the external device, Vehicle position measuring means for measuring the vehicle position, means for monitoring whether the current time is the map information request time, and when the current time is the map information request time, the map identifier and the vehicle position are externally Means for transmitting to the device, the map information of the map identifier is obtained from the external device and displayed on the display means, and determined from the external device in consideration of the traveling speed calculated based on the vehicle position Means is provided for acquiring and storing the next map information request time and the identifier of the map information, and thereafter repeating the above operation using the map information request time and the identifier of the map information.
[0010]
A third aspect of the present invention is a map display method in which map information around the vehicle position is sequentially acquired from an external device in accordance with the travel of the vehicle and displayed on the display screen of the navigation device. In this map display method, the navigation device acquires the time for requesting the next map information and the identifier of the map information from an external device in advance, measures the vehicle position, and the current time is the map information request time. When the current time is the map information request time, the map identifier and the vehicle position are transmitted to the external device. The external device transmits the map information of the map identifier to the navigation device, calculates the traveling speed based on the vehicle position, determines the next map information request time based on the traveling speed, and The information request time and the identifier of the next map information are transmitted to the navigation device, and the navigation device displays a map on the display screen based on the map information acquired from the external device, and the map information request time and the map information request time The identifier of the next map information is acquired and the above operation is repeated.
According to the first to third aspects of the present invention, the calculation load on the navigation device side can be reduced, and maps and guidance route information are displayed on the navigation device at an appropriate timing in consideration of road conditions, traveling speeds, accident conditions, and the like. can do.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic explanatory diagram of the present invention.
▲ 1 ▼ First, from the in-vehicle equipment (navigation device) NAV, send your location (place of _{departure) P ST} and the destination _{P DT} to the server device SEV.
(2) The server SEV calculates a route to the destination, determines a necessary map (= MP1 to MPn) along the route, a distribution point of each map, and a distribution time (= T1 to Tn) Calculate At this time, since the road condition, the personality of the driver (whether or not he likes high speed driving), etc. are unknown, the map i (i = 1 to n) is assumed on the assumption that the vehicle will travel at the specified maximum speed when calculating the route. ) Is calculated and stored in the table.
(3) Next, the server SEV sends the map 1 identifier (= MP1) required next and the time (= T1) for requesting the map 1 as a pair to the navigation device NAV. At this time, map information of map 0 and guidance route information necessary at the present time T0 are also transmitted to the navigation device NAV.
[0012]
(4) The navigation device NAV displays the map around the vehicle and the guidance route on the display screen using the received map information of the map 0 and the guidance route information, and monitors whether the current time is equal to the map request time T1. .
(5) If the current time is equal to the map request time T1, the navigation device NAV sends the map identifier (= MP1) and the current vehicle position (= P1) as a set to the server SEV, and the map 1 (= MP1) is requested to download map information.
(6) The server SEV downloads the requested map information (= MP1) of the requested map and the guidance route information to the navigation device, and also changes the vehicle position P1 at the time T1 and the vehicle position P0 at the previous time T0. Based on the travel speed, the next map information request time T2 is determined, and the map information request time (= T2) and the identifier of the next map 2 (= MP2) are sent to the navigation device. Send to NAV.
[0013]
(7) The navigation device displays the map and the guide route on the display screen based on the map information and guide route information of the map 1 (= MP1) acquired from the server, and similarly the map information request time acquired from the server. Based on (= T2) and the identifier (= MP2) of the map information, the operations after (4) are repeated.
That is, the navigation device NAV displays the map around the vehicle and the guidance route on the display screen using the received map information and guidance route information of the map 1, and monitors whether the current time is equal to the map request time T2.
(8) If the current time is equal to the map request time T2, the navigation device NAV sends the map identifier (= MP2) and the vehicle position (= P2) as a set to the server SEV, and the next map 2 ( = MP2) The map information download is requested. The same applies hereinafter.
[0014]
FIG. 2 is a block diagram of a system including an offboard navigation apparatus according to the present invention. The offboard navigation apparatus 1 can communicate with a base station 2 via a mobile telephone network, and the base station 2 is connected via the Internet (IP network) 3. Can communicate with the server. The offboard navigation device 1 connects to the server 4 as described in FIG. 1 as necessary, acquires map information and a guidance route from the server, and displays the map and the guidance route on the display screen.
[0015]
In the off-board navigation device 1, 11 is a processor, 12 is a ROM for storing various programs and fixed data, 13 is a RAM for storing processing results and guidance route information, 14 is a communication interface, and 15 is a self-detecting vehicle position. A vehicle position detection unit, 16 is a map information memory for storing map information received from the server, 17 is a display controller for generating various images, 18 is a monitor, 19 is an operation unit such as a remote controller, a touch screen, or a hard key.
[0016]
FIG. 3 is a flowchart of the map display processing of the present invention, the left side is the processing flow of the offboard navigation apparatus 1, and the right side is the processing flow of the server 2.
Prior to departure, the navigation device 1 sends the current location (departure location) _PST and the destination location _PDT to the server device 4 to request a map and guidance route information (step 101), i = 1 (step 102), It waits for download of map information, guide route information, etc. from the server 4 (step 103). The current time T0 will be described as the departure time. However, the departure time may be input separately, or the vehicle start time may be set as the departure time.
The server 4 monitors whether there is a guidance request such as a map (step 201), and if there is a guidance request, i = 1 (step 202). Next, a route to the destination is calculated, a necessary map is determined along the route, and a distribution point of each map and a time when the navigation device requests a map are calculated. Then, the server 4 sends the map i identifier (= MPi) required next and the time (= Ti) for requesting the map i to the navigation device 1 as a pair. The server 4 also transmits map information and guidance route information of the map i-1 (= MPi-1 = MP0) required at the current time Ti-1 (= T0) to the navigation device 1 (step 203). Thereafter, it waits for the next map request (step 204).
[0017]
After the processing in step 203, the navigation device 1 receives the map i-1 identifier (= MPi) from the server 4 in step 103, the time for requesting the map i (= Ti), and the map i-1 required at the current time Ti-1. Receive information and guidance route information. As a result, the navigation device 1 displays the map and the guidance route around the vehicle on the display screen using the map information and guidance route information of the map i-1 required at the current time Ti-1 (step 104). Next, it is monitored whether the current time becomes equal to the map request time Ti (step 105).
[0018]
Thereafter, the processing after step 104 is repeated until the current time becomes equal to the map request time Ti. Then, if the current time is equal to the map request time Ti, the “identifier of map i (= MPi)” and the current vehicle position Pi received and stored in step 103 are transmitted to the server 4 to store the map i. Download is requested (step 106). Thereafter, i is incremented by i + 1 → i (step 107), and download of map information, guide route information, etc. from the server 4 is awaited (step 103).
If there is a next map request from the navigation device 1 in the process of step 106, the server 4 will be “YES” in step 204, and the vehicle position Pi-1 at the time Ti and the vehicle position Pi-1 at the previous time Ti-1. The travel speed S is calculated based on (step 205), and i is incremented by i + 1 → i (step 206).
[0019]
Next, the server 4 downloads the map information and the guide route information of the map i-1 (= MPi-1) requested in Step 106 to the navigation device, and at the next map information request time based on the traveling speed S. Ti is determined, and the map information request time (= Ti) and the identifier of the next map i (= MPi) are transmitted to the navigation device 1 (step 207).
The map information request time Ti is determined as follows. That is, since the distribution point where the map i is to be downloaded is known, the next map information request time Ti is calculated by calculating the distance L between the current vehicle position and the distribution point and dividing the distance L by the traveling speed S. Can be determined. Next, the server 4 checks whether the final map including the destination has been transmitted (step 208). If “NO”, the server 4 returns to step 204 and waits for the next map request.
[0020]
In step 103, the navigation device 1 sends an identifier (= MPi) of the next required map i from the server 4, a time (= Ti) for requesting the map i, and a map i−1 ( = MPi-1) If the map information and the guide route information are received, the processing after step 104 is repeated.
Thereafter, the navigation device 1 repeats the processing after step 103 until it reaches the destination, and the server device repeats the processing after step 204 until “YES” at step 208.
[0021]
The above is a case where a map request and map download are performed at a map distribution point predicted by the server, but the traveling speed changes due to a traffic jam or an accident. In such a case, the map request or map download may not be performed at the map distribution point predicted by the server. FIG. 4 is an explanatory diagram of server processing in such a case.
The map distribution points A1 to An where the map i (= 1 to n) is to be downloaded are known.
This is because when the server 4 calculates the guidance route, the identifier (= MPi) of the map i (i = 1 to n) required to reach the destination from the departure point and the map distribution point Ai to be downloaded This is because (i = 1 to n) is determined and stored.
[0022]
If the distance between each map distribution point is Li, the time predicted to pass through each map distribution point Ai (i = 1 to n) is Ti, and the map distribution point A2 is run as predicted, the map distribution point The vehicle speed S assumed by the server 4 at A2 is S = L1 / (T2-T1)
It becomes. The time T3 to reach the next map distribution point A3 is expressed by the following equation T3 = T2 + (L2 / S)
It is obtained by. However, if the traveling speed becomes low due to traffic jams, accidents, etc., and the vehicle is at point A3 ′ at time T3, the navigation device requests download of the next map 3 (= MP3) at this point A3 ′, The server downloads the map 3. At this time, the server 4 needs to determine the map request time T4 of the next map 4 (= MP4) together with the download of the map 3, and notify the navigation device. The server 4 determines T4 as follows. L2 ′ is the distance from the map distribution point A2 to the point A3 ′.
[0023]
First, the vehicle speed S 'is expressed by the following equation S' = L2 '/ (T3-T2)
Recalculate with Using this vehicle speed S ′, the map request time T4 of the map 4 (= MP4) is given by the following equation: T4 = T3 + (L2−L2 ′ + L3) / S ′
Can be determined.
In this way, even if the vehicle speed changes due to traffic jams, accidents, etc., the server always estimates the next map request time in consideration of the changing vehicle speed and notifies the navigation device of the next map request time. It is only necessary to attach the position of the vehicle at the notified time and request a map from the server. A desired map can be obtained in a timely manner, and the load on the navigation device can be reduced.
[0024]
Since the server 4 is flooded with requests from a large number of in-vehicle devices (navigation devices), if the map request times of the respective navigation devices are matched, processing may be delayed and a problem may occur. Considering this situation, the map request time of each navigation device is shifted by the time ΔT required for processing. In this way, problems due to processing delay can be solved.
[0025]
【The invention's effect】
As described above, according to the present invention, the server estimates the next map request time in consideration of the constantly changing vehicle speed and notifies the navigation device of the next map request time, and the navigation device pastes the vehicle position at the notified time. You just need to request a map from the server. As a result, according to the present invention, the memory capacity for storing the map can be reduced, and an expensive CPU requiring high-speed processing is not required, and the navigation device can be configured to be small and inexpensive.
In addition, according to the present invention, it is only necessary to paste the vehicle position at the time notified by the server and request the map from the server. Even if the vehicle speed changes due to traffic congestion or an accident, the desired map is Well, it can be obtained without interruption.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory diagram of the present invention.
FIG. 2 is a configuration diagram of a system including the off-board navigation device of the present invention.
FIG. 3 is a flowchart of map display processing of the present invention.
FIG. 4 is a process explanatory diagram of a server.
FIG. 5 is an explanatory diagram of a conventional communication navigation (prior art 1).
[Explanation of symbols]
SEV server NAV Navigation device MPi Map identifier Ti of map i Download request time Pi of map i Own vehicle position

Claims (4)

In the map display method of the navigation device for acquiring and displaying map information around the own vehicle position sequentially from an external device according to the traveling of the vehicle,
Obtain the time for requesting the next map information and the identifier of the map information from an external device in advance,
Measure the vehicle position and monitor whether the current time is the map information request time,
When the current time is the map information request time, the map identifier and the vehicle position are transmitted to an external device,
The next map information request time determined by taking the travel speed calculated based on the vehicle position from the external device while acquiring the map information of the map identifier from the external device and displaying it on the display device And a map display identifier for the map information. The map display method for a navigation device, wherein the map information is acquired and stored, and thereafter the above operation is repeated. In a navigation device that acquires and displays map information around the vehicle position sequentially from an external device according to the traveling of the vehicle,
Display means for sequentially displaying map information around the vehicle position in accordance with the traveling of the vehicle;
Means for acquiring in advance the time for requesting the next map information and the identifier of the map information from the external device;
Own vehicle position measuring means for measuring own vehicle position,
Means for monitoring whether the current time is the map information request time;
Means for transmitting the map identifier and the vehicle position to an external device when the current time is the map information request time;
The next map information request time determined by taking the travel speed calculated based on the vehicle position from the external device and acquiring the map information of the map identifier from the external device and displaying it on the display means And a map information identifier. The navigation apparatus comprising means for acquiring and storing the map information and repeating the operation thereafter. In a map display method for acquiring map information around the vehicle position sequentially from an external device according to the traveling of the vehicle and displaying it on the display screen of the navigation device,
The navigation device acquires the time for requesting the next map information and the identifier of the map information from the external device in advance, measures the vehicle position, and monitors whether the current time is the map information request time, When the current time is the map information request time, the map identifier and the vehicle position are transmitted to an external device,
The external device transmits the map information of the map identifier to the navigation device, calculates the traveling speed based on the vehicle position, determines the next map information request time based on the traveling speed, and Send the information request time and the identifier of the next map information to the navigation device,
The navigation device displays a map on the display screen based on the map information acquired from the external device, and acquires the map information request time and the identifier of the next map information, and repeats the above operation. A map display method in the navigation system. 4. The map display method and navigation device according to claim 1, wherein the guide route information is acquired from an external device and displayed on a map.

Images