Route searching device

• US 6,222,836 B1
• Filed: 03/23/1998
• Issued: 04/24/2001
• Est. Priority Date: 04/04/1997
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Sekiyama, Hiroaki, Sugimoto, Hironobu
• Primary Examiner(s): TON, DANG T
• Application Number:
  US09/045,789
• Time in Patent Office: 1,128 Days
• Field of Search: 370/351, 370/352, 370/254, 370/252, 370/389, 370/395, 370/400, 370/248, 370/229, 370/230-235, 370/237, 370/238, 370/239, 370/349, 370/428, 370/412, 370/404
• US Class Current: 370/351
• CPC Class Codes: G01C 21/3492 employing speed data or traffic data, e.g. real-time or historical traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968
• CPC Class Codes: G08G 1/096827 where the route is computed onboard

Abstract

A device searches for an optimum route by estimating traffic information of a link whose traffic information cannot be obtained based on information from another link. Traffic information, such as a degree of congestion of link and a travelling time of link, is obtained by means of a transceiver, a FM antenna, and a receiver, and the optimum route is searched by an ECU for navigation. When there is a second link whose traffic information can not be obtained among links for searching routes, weighting of traffic information of a first link is performed according to a directional difference and a degree of separation (time or distance) between the first link and the second link, and then traffic information of the second link is estimated based on the traffic information weighted. The ECU for navigation searches the optimum route to destination using the traffic information estimated and displays it on a display.

Claims

1. A route searching device for searching for a route to a destination comprising:

storage means for storing link data that relates to vehicular traffic information in links of a traffic route;

arithmetic means for computing traffic information of a second link having no traffic information by carrying out weighting of traffic information of a first link having traffic information stored in the storage means according to a directional difference and a degree of separation between said first link and said second link, the directional difference relating to a physical difference in direction between the first and second links and the degree of separation relating to an amount of physical separation between the first and second links; and

search means for searching a route to said destination by using said first link and said second link.

2. The route searching device according to claim 1, wherein said weighting is the largest at a location of said first link and decreases from said location with increase of said degree of separation or said directional difference.

3. The route searching device according to claim 1, said device further comprising detecting means for detecting a change of said traffic information of said first link with passage of time, and wherein said arithmetic means carries out weighting of said traffic information of said first link based on the change of said traffic information with passage of time.

5. The route searching device according to claim 1, wherein said storage means stores statistical data of said traffic information, and said arithmetic means carries out weighting of said traffic information of said first link based on said statistical data.

7. The route searching device according to claim 1, wherein said arithmetic means decreases step by step weighting of traffic information of said first link according to said degree of separation when said directional difference is substantially zero.

8. The route searching device according to claim 1, wherein said traffic information is a degree of congestion.

9. The route searching device according to claim 1, wherein said traffic information is link travelling time.

10. The route searching device according to claim 1, wherein said degree of separation is a time interval between said first link and said second link.

11. The route searching device according to claim 1, wherein said degree of separation is a physical distance between said first link and said second link.

4. A route searching device for searching for a route to a destination comprising:

storage means for storing link data;

arithmetic means for computing traffic information of a second link having no traffic information by carrying out weighting of traffic information of a first link found in said link data according to a directional difference and a degree of separation between said first link and said second link;

search means for searching a route to said destination by using said first link and said second link,

detecting means for detecting a change of said traffic information of said first link with passage of time, wherein said arithmetic means carries out weighting of said traffic information of said first link based on the change of said traffic information with passage of time,

wherein said weighting value is greatest at the location of said first link and decreases from said location with increase of said degree of separation or said directional difference;

when said change of said traffic information with passage of time is positive, a degree of decrease of time; and

, when said change of said traffic information with passage of time is negative, a degree of decrease is more than when traffic information does not change with passage of time.

6. A route searching device for searching for a route to a destination composing:

storage means for storing link data;

arithmetic means for computing traffic information of a second link having no traffic information by carrying out weighting of traffic information of a first link found in said link data according to a directional difference and a degree of separation between said first link and said second link; and

search means for searching a route to said destination by using said first link and said second link,

wherein said storage means stores statistical data of said traffic information, and said arithmetic means carries out weighting of said traffic information of said first link based on said statistical data, and

wherein said weighting value is greatest at a location of said first link and decreases from said location with increase of said degree of separation or said directional difference in such a manner that said weighting coincides with said statistical data.

12. A route searching device for searching for a route to a destination comprising:

a data base for storing link data that relates to vehicular traffic information in links of a traffic route;

a computer for computing traffic information of a second link having no traffic information by carrying out weighting of traffic information of a first link having traffic information stored in the storing means according to a directional difference and/or a degree of separation between said first link and said second link, the directional difference relating to a physical difference in direction between the first and second links and the degree of separation relating to an amount of physical separation between the first and second links, and for searching a route to said destination by using said first link and said second link.

13. The route searching device according to claim 12, wherein said computer carries out weighting of traffic information of said first link based on a change of said traffic information with passage of time.

14. The route searching device according to claim 12, wherein said computer carries out traffic information of said first link based on statistical data of said traffic information.