Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
221 words
A radius of curvature detecting apparatus for a
vehicle guidance system, the apparatus being adapted to
detect curves in the road ahead of said vehicle based on
road information obtained from a vehicle navigation system,
comprising: means for detecting a first point (P 1 ), a second
point (P 2 ) and a third point (P 3 ) in order of travelling
direction of said vehicle from point data showing a road
configuration and provided by said vehicle navigation
system; means for comparing the length of the straight line
connecting said first point and said second point with the
length of the straight line connecting said second point and
said third point and for determining which is shorter and
which is longer; mid-point calculating means for finding a fourth
point (P 12 ) located at a distance halfway along said shorter
line from said second point; equivalent mid-point calculating means for finding a
fifth point (P 23 ) located at said distance from said second
point in the direction of said longer line; and radius of curvature calculating means for determining
a point of intersection (O 2 ) 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 (R) based on said center of said curve.
Claim 2
Dependent Claim
71 words
The radius of curvature detecting apparatus
according to claim 1, further comprising: radius of curvature correcting means for correcting
said radius of curvature calculated in said radius of
curvature calculating means, when the difference between the
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.
Claim 3
Dependent Claim
23 words
The radius of curvature detecting apparatus
according to claim 2, wherein said predetermined allowable error value varies in
accordance with a road width.
Claim 4
Dependent Claim
26 words
The radius of curvature detecting apparatus
according to claim 2, wherein said predetermined allowable error value varies in
accordance with the length of said shorter line.
Claim 5
Dependent Claim
23 words
The radius of curvature detecting apparatus
according to claim 3, wherein said road width is established based on data
obtained from image information.
Claim 6
Dependent Claim
29 words
The radius of curvature detecting apparatus
according to claim 3, wherein said road width is established based on data obtained
from a road map stored in said navigation system.
Claim 7
Independent Claim
173 words
A 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 (P 1 ), a second point (P 2 )
and a third point (P 3 ) from said point data; comparing the length of the straight line connecting
said first point and said second point with the length of
the straight line connecting said second point and said
third point and determining which is shorter and which is
longer; finding a fourth point (P 12 ) located at a distance
of said shorter line from said second point; finding a fifth point (P 23 ) located at said distance
from said second point in the direction of said longer line;
and determining a point of intersection (O 2 ) of
perpendicular lines from said fourth point and said
fifth point, respectively, as a center of said curve and
calculating a radius of curvature (R) based on said center
of said curve.
Claim 8
Dependent Claim
63 words
A method of detecting a radius of curvature
according to claim 7, further comprising the steps of: correcting said calculated radius of curvature when
the difference between the 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.