Radius of curvature detecting apparatus and the method thereof

• US 6,138,084 A
• Filed: 06/10/1998
• Issued: 10/24/2000
• Est. Priority Date: 06/12/1997
• Status: Expired due to Fees

• Current Assignee: Fuji Jukogyo KK (Subaru Corp.)
• Original Assignee: Fuji Jukogyo KK (Subaru Corp.)
• Inventors: Mine, Atsushi
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): Bui, Bryan
• Application Number:
  US09/095,529
• Time in Patent Office: 867 Days
• Field of Search: 702/157, 702/158, 702/149, 702/150, 701/1, 701/201, 701/206, 701/207, 701/208, 701/209, 701/210, 340/210, 340/988, 340/995
• US Class Current: 702/157
• CPC Class Codes: B60W 40/072 Curvature of the road
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network

Abstract

A radius of curvature detecting apparatus and method of a vehicle for detecting a radius of curvature of a curve based on road information obtained from a vehicle navigation system comprises, three-points detection of a first point, a second point and a third point in order of traveling direction of the vehicle from point data showing a road configuration which are provided by the vehicle navigation system, distance comparison of a distance of a straight line connecting the first point and the second point with a distance of a straight line connecting the second point and the third point and for determining a short straight line and a long straight line, respectively, mid-point calculation for finding a mid-point point located at a half distance of the short straight line from the second point, equivalent mid-point calculation for finding an equivalent mid-point located at the half distance from the second point on the long straight line, and radius of curvature calculation for determining a point of intersection of perpendicular lines from the mid-point point and the equivalent mid-point as a center of the curve and for calculating a radius of curvature based on the center of the curve. The calculated radius of curvature is corrected, for example when the road width is small or the distance of the short straight line is large.

Claims

1. A radius of curvature detecting apparatus of a vehicle for detecting a radius of curvature of a curve located ahead of said vehicle based on road information obtained from a vehicle navigation system, comprising:

three-points detecting means for detecting a first point, a second point and a third point in order of traveling direction of said vehicle from point data showing a road configuration and provided by said vehicle navigation system, said first point and said third point being located on said road configuration, and said second point being located away from said curve to define a first tangent to the curve with the first point and to define a second tangent to the curve with the third point;

distance comparing means for comparing a distance of a straight line connecting said first point and said second point with a distance of a straight line connecting said second point and said third point and for determining a short straight line and a long straight line, respectively;

mid-point calculating means for finding a fourth point located at a half distance of said short straight line from said second point;

equivalent mid-point calculating means for finding a fifth point located at said half distance from said second point on said long straight line; and

radius of curvature calculating means for determining a point of intersection of perpendicular lines from said fourth point and said fifth point, respectively, as a center of said curve and for calculating a radius of curvature based on said center of said curve.

2. A radius of curvature detecting apparatus of a vehicle for detecting a radius of curvature of a curve located ahead of said vehicle based on road information obtained from a vehicle navigation system, comprising:

three-points detecting means for detecting a first point, a second point and a third point in order of traveling direction of said vehicle from point data showing a road configuration and provided by said vehicle navigation system;

distance comparing means for comparing a distance of a straight line connecting said first point and said second point with a distance of a straight line connecting said second point and said third point and for determining a short straight line and a long straight line, respectively;

mid-point calculating means for finding a fourth point located at a half distance of said short straight line from said second point;

equivalent mid-point calculating means for finding a fifth point located at said half distance from said second point on said long straight line;

radius of curvature calculating means for determining a point of intersection of perpendicular lines from said fourth point and said fifth point, respectively, as a center of said curve and for calculating a radius of curvature based on said center of said curve; and

radius of curvature correcting means for correcting said radius of curvature calculated in said radius of curvature calculating means, when a difference between a distance from said center of curvature to said second point and said radius of curvature exceeds a predetermined allowable error value, in such a way that said difference agrees with said predetermined allowable error value.

3. The radius of curvature detecting apparatus according to claim 2, wherein

said predetermined allowable error value varies in accordance with a road width.

4. The radius of curvature detecting apparatus according to claim 3, wherein

said road width is established based on data obtained from an image information.

5. The radius of curvature detecting apparatus according to claim 3, wherein

said road width is established based on data obtained from a road map in said navigation system.

6. The radius of curvature detecting apparatus according to claim 2, wherein

said predetermined allowable error value varies in accordance with a distance of said short straight line.

7. A radius of curvature detecting method of detecting a radius of curvature of a curve of a road based on point data showing a configuration of said road, comprising the steps of:

detecting a first point, a second point and a third point from said point data, said first point and said third point being located on said road configuration, and said second point being located away from said curve to define a first tangent to the curve with the first point and to define a second tangent to the curve with the third point;

comparing a distance of a straight line connecting said first point and said second point with a distance of a straight line connecting said second point and said third point and determining a short straight line and a long straight line, respectively;

finding a fourth point located at a half distance of said short straight line from said second point;

finding a fifth point located at said half distance from said second point on said long straight line; and

determining a point of intersection of perpendicular lines from said fourth point and said fifth point, respectively, as a center of said curve and calculating a radius of curvature based on said center of said curve.

8. A radius of curvature detecting method of detecting a radius of curvature of a curve of a road based on point data showing a configuration of said road, comprising the steps of:

detecting a first point, a second point and a third point from said point data;

comparing a distance of a straight line connecting said first point and said second point with a distance of a straight line connecting said second point and said third point and determining a short straight line and a long straight line, respectively;

finding a fourth point located at a half distance of said short straight line from said second point;

finding a fifth point located at said half distance from said second point on said long straight line;

determining a point of intersection of perpendicular lines from said fourth point and said fifth point, respectively, as a center of said curve and calculating a radius of curvature based on said center of said curve; and

correcting said calculated radius of curvature when a difference between a distance from said center of curvature to said second point and said radius of curvature exceeds a predetermined allowable error value, in such a way that said difference agrees with said predetermined allowable error value.