Apparatus for predicting road shape
An apparatus for predicting road shape includes a map data reading unit, a clothoid curve calculating unit for calculating a clothoid curve corresponding to a corner area, and a fitting unit for adjusting the clothoid curve to the corner area. The clothoid curve calculating unit calculates a clothoid curve by using X-coordinates and Y-coordinates which are found by expressions: x = X 0 + ∑ L cos ϕ ( 1 ) and y = Y 0 + ∑ L · sin ϕ , ( 2 ) wherein X 0 and Y 0 are coordinates at a start point of a clothoid curve, L is distance from the start point of the clothoid curve, φ is computed by equation (3) φ=α+2kL, wherein α is an angle for the start point of the clothoid curve and “k” is computed by equation (4) k =28/A 2 , wherein A is a clothoid coefficient.
1. An apparatus for predicting road shape, comprising:
a map data reading unit for reading map data;
a clothoid curve calculating unit for calculating a clothoid curve corresponding to a corner area based on said map data; and
a fitting unit for adjusting said clothoid curve to said corner area; and
wherein the clothoid curve calculating unit obtains a clothoid coefficient corresponding to the minimum radius of said corner area from a table which is produced based on a relation between a radius of said corner area on an actual road and a clothoid coefficient of a clothoid curve.
2. The apparatus for predicting road shape according to claim 1 further comprising:
a start point position detecting unit for detecting a position of a start point or end point of said corner area based on said clothoid curve adjusted to said corner area.
3. The apparatus for predicting road shape according to claim 1 , wherein the fitting unit adjusts said clothoid curve to a start part or end part of said corner area.
4. The apparatus for predicting road shape according to claim 2 , wherein the fitting unit adjusts said clothoid curve to a start part or end part of said corner area.
5. The apparatus for predicting road shape according to claim 1 , wherein the clothoid curve calculating unit calculates a clothoid curve by using X-coordinates and Y-coordinates which are found by the following approximate expressions (1) and (2):
X
=
X
0
+
∑
L
cos
ϕ
(
1
)
Y
=
Y
0
+
∑
L
cos
ϕ
(
2
)
wherein X 0 and Y 0 are X-Y coordinates at a start point of a clothoid curve, L is a distance from the start point of the clothoid curve, φ is computed by the following equation (3):
φ=α+2 kL (3)
wherein α is an angle for the start point of the clothoid curve and “k” is computed by the following equation (4):
k
=
28
A
2
(
4
)
wherein A is a clothoid coefficient.
6. The apparatus for predicting road shape according to claim 1 further comprising:
a predicted result database for storing data obtained by each operation of the clothoid curve calculating unit, fitting unit, and start point position detecting unit.
7. An apparatus for predicting road shape, comprising:
a map data reading unit for reading map data;
a clothoid curve calculating unit for calculating a clothoid curve corresponding to a corner area based on said map data; and
a fitting unit for adjusting said clothoid curve to said corner area; and
wherein the clothoid curve calculating unit calculates a clothoid curve by using X-coordinates and Y-coordinates which are found by the following approximate expressions (1) and (2):
X
=
X
0
+
∑
L
cos
ϕ
(
1
)
Y
=
Y
0
+
∑
L
cos
ϕ
(
2
)
wherein X 0 and Y 0 are X-Y coordinates at a start point of a clothoid curve, L is a distance from the start point of the clothoid curve, φ is computed by the following equation (3):
φ=α+2 kL (3)
wherein α is an angle for the start point of the clothoid curve and “k” is computed by the following equation (4):
k= 28 /A 2 (4)
wherein A is a clothoid coefficient.
8. The apparatus for predicting road shape according to claim 7 further comprising:
a predicted result database for storing data obtained by each operation of the clothoid curve calculating unit, fitting unit, and start point position detecting unit.
9. The apparatus for predicting road shape according to claim 7 further comprising:
a start point position detecting unit for detecting a position of a start point or end point of said corner area based on said clothoid curve adjusted to said corner area.
10. The apparatus for predicting road shape according to claim 7 , wherein the fitting unit adjusts said clothoid curve to a start part or end part of said corner area.
11. A method of calculating a clothoid curve comprising:
(a) calculating a clothoid curve corresponding to a corner area based on map data using a program controlled computer; and
calculating the clothoid curve using X-coordinates and Y-coordinates which are found by the following approximate expressions (1) and (2):
X
=
X
0
+
∑
L
cos
ϕ
(
1
)
Y
=
Y
0
+
∑
L
cos
ϕ
(
2
)
wherein X 0 and Y 0 are X-Y coordinates at a start point of a clothoid curve, L is a distance from the start point of the clothoid curve, φ is computed by the following equation (3):
φ=α+2 kL (3)
wherein α is an angle for the start point of the clothoid curve and “k” is computed by the following equation (4):
k
=
28
A
2
(
4
)
wherein A is a clothoid coefficient.