Route guidance apparatus and method

• US 20030236616A1
• Filed: 03/19/2003
• Published: 12/25/2003
• Est. Priority Date: 03/19/2002
• Status: Active Grant

• Current Assignee: Pioneer Corporation
• Original Assignee: Pioneer Corporation
• Inventors: Kawakami, Takashi, Hashida, Masaya
• Granted Patent: US 6,934,627 B2
• Time in Patent Office: Days
• US Class Current: 701/209
• CPC Class Codes: G01C 21/3632 Guidance using simplified or iconic instructions, e.g. using arrows G01C21/365 takes precedence

Abstract

When a moving body (e.g., a car) is entering a roundabout, a navigation machine extracts link data of the roundabout from road map data. The navigation machine detects a route entering the roundabout (i.e., a route the moving body is currently taking), a center of the roundabout, and an exiting route based on the link data to determine an angle of the exiting route with respect to the entering route. A direction mark having the exiting route angle is prepared as a heading direction guidance image. The navigation machine can show an appropriate route (direction) at the roundabout without increasing the amount of stored image data.

Claims

1. A route guidance apparatus for displaying a heading direction guidance image on a display unit when a moving body enters a roundabout having a plurality of branching routes extending from the roundabout, the moving body taking a first route of the plurality of branching routes to enter the roundabout and a second route of the plurality of branching routes to exit the roundabout, the apparatus comprising:

a link data extractor for extracting link data of the roundabout from road map data;

a calculator for determining an angle between the first and second routes based on the link data as an exiting angle of the roundabout; and

an image generator for preparing a first image showing a direction of the exiting angle as the heading direction guidance image.

2. The route guidance apparatus according to claim 1, wherein the image generator further generates a second image of the roundabout and a third image of the first route, the first image being an exiting mark and the third image being an entering route mark, and the image generator creating a combined image of the first, second and third images such that the exiting mark is angularly spaced from the entering route mark by the exiting angle with respect to a center of the roundabout.

3. The route guidance apparatus according to claim 1 further comprising a controller for superposing the heading direction guidance image over a map displayed by the display unit.

4. The route guidance apparatus according to claim 2 further comprising a controller for superposing the combined image over a map displayed by the display unit.

5. A route guidance method for displaying a heading direction guidance image on a display unit when a moving body enters a roundabout having a plurality of branching routes extending from the roundabout, the moving body taking a first route of the plurality of branching routes to enter the roundabout and a second route of the plurality of branching routes to exit the roundabout, the method comprising:

extracting link data of the roundabout from road map data;

calculating an angle between the first and second routes based on the link data as an exiting angle of the roundabout; and

preparing a first image showing a direction of the exiting angle as the heading direction guidance image.

6. The route guidance method according to claim 5 further comprising preparing a second image of the roundabout and a third image of the first route, and preparing a combined image of the first, second and third images such that an exiting mark is angularly spaced from an entering route mark by the exiting angle with respect to a center of the roundabout.

7. The route guidance method according to claim 5 further comprising superposing the heading direction guidance image over a map displayed by the display unit.

8. The route guidance method according to claim 6 further comprising superposing the combined image over a map displayed by the display unit.

9. A navigation apparatus for a vehicle, comprising:

a data storage for storing road map data;

a detector for determining a current location of the vehicle;

a display unit for displaying a road map of a certain area including the current location of the vehicle, data of the road map of the certain area being retrieved from the road map data;

a car mark generator for superposing a car mark at the current location of the vehicle on the displayed road map;

a data extractor for extracting data of a roundabout having a plurality of branching routes extending from the roundabout from the road map data when the vehicle enters the roundabout, the vehicle taking a first route of the plurality of branching routes to enter the roundabout and a second route of the plurality of branching routes to exit the roundabout;

a calculator for determining an angle between the first and second routes based on the data of the roundabout;

an image generator for preparing a first image showing a direction of the angle; and

a controller for superposing the first image over the displayed road map.

10. The navigation apparatus according to claim 9, wherein the image generator further generates a second image of the roundabout and a third image of the first route, the first image being an exiting mark and the third image being an entering route mark, the controller creates a combined image of the first, second and third images such that the exiting mark is angularly spaced from the entering route mark by the angle with respect to a center of the roundabout, and the controller superposes the combined image over the displayed road map.

11. The navigation apparatus according to claim 9, wherein the second route is determined in accordance with an optimal route connecting the current location of the vehicle to a destination specified by a user of the navigation apparatus.

12. The navigation apparatus according to claim 9, wherein the detector determines the current location of the vehicle based on a GPS.

13. The navigation apparatus according to claim 9, wherein the image generator does not prepare the heading direction guidance image when the car navigation apparatus does not determine an optimal route from the current location of the vehicle to a destination.