Route search device and route search method

• US 8,185,299 B2
• Filed: 07/24/2008
• Issued: 05/22/2012
• Est. Priority Date: 07/25/2007
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Xanavi Informatics Corporation (Hitachi, Ltd.)
• Inventors: Fujiwara, Junsuke, Fushiki, Takumi, Endo, Yoshinori
• Primary Examiner(s): O'Connor, Gerald J.
• Assistant Examiner(s): PASS, NATALIE
• Application Number:
  US12/179,389
• Publication Number:
  US 20090037100A1
• Time in Patent Office: 1,398 Days
• Field of Search: 701200-202, 701/204, 701209-211, 701/301, 340/995.13, 340/905
• US Class Current: 701/202
• CPC Class Codes: G01C 21/3453 Special cost functions, i.e. other than distance or default speed limit of road segments
• 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
• CPC Class Codes: G08G 1/096844 where the complete route is dynamically recomputed based on new data

Abstract

A route to a destination in which required travel time barely varies depending on weather is searched for without referring to weather forecast or weather information. A route search device comprises following means: a storage medium for storing traffic information including travel times by weather conditions for each link comprising a road on a map; a pointing device which sets a starting point and a destination; a weather condition-based route search module that determines the shortest travel time route from the starting point to the destination by weather conditions using the traffic information stored in the storage medium; a link series-identifying module that extracts link series which vary with weather conditions from link series comprising the shortest travel time route determined by the weather condition-based route search module, determines the required travel time by weather conditions for the each link series that vary with weather conditions by using the traffic information stored in the storage medium, and identifies a link series whose required travel time barely varies depending on weather conditions; and a link series-registering medium that registers the link series identified by the link series-identifying module as a link series comprising a guide route from the starting point to the destination.

Claims

1. A route search device comprising:

a storage medium for storing traffic information classified by weather conditions;

a pointing device which sets a starting point and a destination; and

a guide route search module that searches routes having a shortest required travel time for a plurality of weather conditions from the starting point to the destination, calculates a plurality of required travel times for each of the weather conditions for each of the searched routes, and selects a route having the smallest amount of variation of the plurality of the required travel times from the searched routes as a guide route by using traffic information stored in the storage medium;

wherein the traffic information stored in the storage medium includes travel time for each link comprising a road on a map under each weather condition, and

wherein the guide route search module includes;

a weather condition-based route search module that determines a shortest travel time route from the starting point to the destination under each weather condition by using the traffic information stored in the storage medium;

a link series-identifying module that extracts link series which vary with weather conditions from link series comprising the shortest travel time route determined by the weather condition-based route search module, determines required travel time for each of the link series that vary with weather conditions by using the traffic information stored in the storage medium, and identifies a link series smallest in the amount of variation in the required travel time for the weather conditions in each of the link series; and

a link series-registering medium for registering a link series identified by the link series-identifying module as a link series comprising the guide route from the starting point to the destination.

2. The route search device according to claim 1,

wherein the link series-identifying module determines the amount of variation in required travel time depending on weather conditions by using difference between a maximum value and a minimum value of required travel times depending on weather conditions for the link series.

3. The route search device according to claim 1,

wherein the link series-identifying module determines the amount of variation in required travel time depending on weather conditions by using a maximum difference between the required travel times depending on weather conditions for the link series and a required travel time under any one of the weather conditions.

4. The route search device according to claim 1,

wherein the link series-identifying module determines the amount of variation in required travel time depending on weather conditions by using a variance or a standard deviation of the required travel times depending on weather conditions for the link series.

5. The route search device according to claim 1, comprising:

a total required travel time-computing unit that determines a total required travel time for each guide route depending on weather conditions by using the traffic information stored in the storage medium; and

a display control unit that displays the total required travel time determined by the total required travel time-computing unit corresponding to weather conditions.

6. The route search device according to claim 1, comprising:

a total required travel time-computing unit that determines a total required travel time for the guide route depending on weather conditions using the traffic information stored in the storage medium; and

a display control unit that determines difference between the total required travel times depending on weather conditions and the average value of the total required travel times and displays the difference.

7. The route search device according to claim 1, comprising:

a total required travel time-computing unit that determines a total required travel time for each guide route depending on weather conditions by using the traffic information stored in the storage; and

a display control unit that determines difference between a required travel time under a specific weather condition and the total required travel times under other weather conditions and displays the difference.

8. The route search device according to claim 1, comprising:

a display control unit that takes a link series that is not included in the guide route among the link series that vary with weather conditions as a block influenced largely by weather conditions, and displays this link series in a different mode from that of the guide route.

9. The route search device according to claim 1, comprising:

a display control unit that displays a menu screen including options for accepting use'"'"'s requests to search for a route in which the required travel time is less influenced by weather conditions.

10. A route search method for a route search device,

including a storage medium for storing traffic information classified by weather conditions,

wherein the route search device carries out:

a step of setting a starting point and a destination; and

a guide route search step of searching routes having a smallest required travel time for a plurality of weather conditions from the starting point to the destination, calculating a plurality of required travel times for each of the weather conditions for each of the searched routes, and selecting a route having the smallest amount of variation of the plurality of the required travel times from the searched routes as a guide route by using traffic information stored in the storage medium;

wherein the traffic information stored in the storage medium includes travel time for each link comprising a road on a map under each weather condition, and wherein the guide route search step includes;

a weather condition-based route search step of determining a shortest travel time route from the starting point to the destination under each weather condition using the traffic information stored in the storage medium;

a link series-identifying step of extracting link series that vary with weather conditions from link series comprising each route determined at the weather condition-based route search step, determining required travel time for each of the link series that vary with weather conditions using the traffic information stored in the storage medium, and identifying a link series smallest in the amount of variation in the required travel time for the weather conditions in each of the link series; and

a link series-registering step of registering a link series identified by the link series-identifying step as a link series comprising the guide route from the starting point to the destination.