Vehicular navigation system

• US 6,466,867 B1
• Filed: 03/15/2000
• Issued: 10/15/2002
• Est. Priority Date: 03/18/1999
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Sakashita, Naohiro
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US09/526,112
• Time in Patent Office: 944 Days
• Field of Search: 701/207, 701/208, 701/209, 701/210, 701/211, 701/117, 340/988, 340/990, 340/995, 731/78.R
• US Class Current: 701/211
• CPC Class Codes: G01C 21/3626 Details of the output of route guidance instructions traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968

Abstract

A navigation system, which can detect particular intersection as the intersection to be guided, even if the particular intersection is not judged as the intersection to be guided in a the Following-the-road judgment. A navigation system includes ECU, which mainly performs a following-the-road judgment and a ramp judgment. In the following-the-road judgment, the ECU determines the particular intersection as the intersection to be guided, when a continuity of the travel road is not secured before and after the intersection. In the ramp judgment,the ECU determines the particular intersection as the intersection to be guided, when the particular intersection is a branch point to an off-ramp, and when there is a merge point within a predetermined distance ahead from the branch point, and further when the recommended guidance route is set so that the vehicle keeps on traveling on the main lane. As a result, the ECU can adequately perform the travel guidance, even if the road has a unique shape such that the branch point is provided close to the merge point and the number of the lanes is increased only between the merge point and the branch point.

Claims

1. A navigation system comprising:

following-the-road judgment means for judging whether a continuity of a travel road is secured before and after a particular intersection when a vehicle passes through the particular intersection existing on a recommended guidance route, and for determining the particular intersection as an intersection to be guided when the continuity of the travel road is not secured;

ramp judgment means for, even when the particular intersection is not determined as the intersection to be guided by the following-the-road means, determining the particular intersection as the intersection to be guided, when the particular intersection is a branch point at which an off-ramp is connected to a main lane to divide traffic on the main lane to the off-ramp, and when there is a merge point at which traffic is merged to the main lane within a predetermined distance ahead of the branch point, and further when the recommended guidance route is set so that the vehicle continues to travel on the main lane;

travel guidance performing means for performing travel guidance regarding the intersection to be guided, which is determined by one of the following-the-road judgment means and the ramp judgment means, when the vehicle approaches the intersection to be guided;

wherein the ramp judgment means first judges whether a certain intersection on the recommended guidance route is the merge point or not, and

when the certain intersection is the merge point, the ramp judgment means uses another particular intersection existing within the predetermined distance on the recommended guidance route from the certain intersection as a possible particular intersection to be judged.

2. A navigation system according to claim 1, wherein the ramp judgment means determines the particular intersection as the intersection to be guided, only when the number of lanes including the main lane is decreased after the particular intersection.

3. A navigation system according to claim 2, wherein the ramp judgment means determines the particular intersection as the intersection to be guided, only when the number of lanes including the main lane is increased only between the on-ramp and the off-ramp.

5. A navigation system according to claim 1, wherein the travel guidance performing means performs the travel guidance by a using voice sound generation apparatus.

6. A navigation system according to claim 5, wherein the travel guidance performing means performs the travel guidance by further using a display unit for displaying characters and images.

4. A navigation system comprising:

following-the-road judgment means for judging whether a continuity of a travel road is secured before and after a particular intersection when a vehicle passes through the particular intersection existing on a recommended guidance route, and for determining the particular intersection as an intersection to be guided when the continuity of the travel road is not secured;

ramp judgment means for, even when the particular intersection is not determined as the intersection to be guided by the following-the-road judgment means, determining the particular intersection as the intersection to be guided, when the particular intersection is a branch point at which an off-ramp is connected to a main lane to divide traffic on the main lane to the off-ramp, and further when the number of lanes including the main lane is decreased after the particular intersection, and when there is a merge point at which traffic is merged to the main lane within a predertermined distance ahead of the branch point;

travel guidance performing means for performing travel guidance regarding the intersection to be guided, which is determined by one of the following-the-road judgment means and the ramp judgment means, when the vehicle approaches the intersection to be guided;

wherein the ramp judgment means firstly judges whether a certain intersection on the recommended guidance route is the merge point or not, and

when the certain intersection is the merge point, the ramp judgment means uses another particular intersection existing within the predetermined distance on the recommended guidance route from the certain intersection as a possible particular intersection to be judged.

7. A navigation system comprising:

following-the-road judgment means for judging whether a continuity of a travel road is secured before and after a particular intersection when a vehicle passes through the particular intersection existing on a recommended guidance route, and for determining the particular intersection as an intersection to be guided when the continuity of the travel road is not secured;

a ramp judgment portion for judging whether the particular intersection is a branch point at which an off-ramp is connected to a main lane to divide traffic on the main lane to the off-ramp, for judging whether there is a merge point at which traffic is merged to the main lane within a predetermined distance ahead from the branch point, for judging whether the recommended guidance route is set so that the vehicle keeps on traveling on the main lane, and for determining the particular intersection as the intersection to be guided when all of the above three judgments are affirmed; and

a travel guidance portion for outputting travel guidance signal regarding the intersection to be guided, which is determined by one of the following-the-road judgment means and the ramp judgment means.

8. A navigation method comprising:

ascertaining that a first possible guidance point on a recommended guidance route is a merge point to a main lane;

ascertaining that a distance from the first possible guidance point to a second possible guidance point on a recommended guidance route is within a predetermined distance;

ascertaining that the second possible guidance point is a branch point;

ascertaining that the determined recommended guidance route includes a particular route on which the vehicle continues to travel on the main lane and passes the branch point; and

performing travel guidance regarding the second possible guidance point.

9. A navigation method comprising:

obtaining data of a first and a second possible guidance points on a recommended guidance route;

judging whether the first possible guidance point is a merge point to a main lane;

calculating a distance from the first possible guidance point to the second possible guidance point, when the first possible guidance point is the merge point;

judging whether the calculated distance is within a predetermined distance;

judging whether the second possible guidance point is a branch point, when the calculated distance is within the predetermined distance;

judging whether the determined recommended guidance route includes a particular route, on which the vehicle further travels the main lane passing the branch point, when the second possible guidance point is the branch point;

determining the second possible guidance point as the intersection to be guided, when the determined recommended guidance route includes the particular route; and

performing travel guidance regarding the intersection to be guided.

10. A navigation method according to claim 9, further comprising:

obtaining data of a third possible guidance point on the recommended guidance route;

calculating a distance from the first possible guidance point to the third possible guidance point when the first possible guidance point is the merge point;

judging whether the third possible guidance point is an additional branch point; and

judging in which particular lane the vehicle travels based upon the data from the first, second and third guidance points.