Vehicle-direction measuring apparatus
First Claim
1. A vehicle-direction measuring apparatus for determining the direction of a vehicle in correspondence with a declination correction value by obtaining the direction of the vehicle on the basis of X-Y coordinate data detected by a vehicle-mounted terrestrial magnetism sensor, said apparatus comprising:
- obtaining means for obtaining the direction of a road on which the vehicle is traveling in correspondence with map data;
calculating means for calculating central coordinate data located on a circle of magnetism, said circle having a center representing a true center of magnetism, based on the direction of the road, a present declination correction value, and said X-Y coordinate data detected by said terrestrial magnetism sensor each time the direction of the road is obtained by said obtaining means;
correcting means for correcting the declination correction value based on outputs of said calculating means to produce a corrected declination correction value; and
means for determining the direction of the vehicle in accordance with an output of said terrestrial magnetism sensor and said corrected declination correction value.
1 Assignment
0 Petitions
Accused Products
Abstract
Central coordinate data located on a circle of magnetism obtained from the X-Y coordinate data detected by a terrestrial magnetism sensor are calculated in correspondence with the direction of the road, calculated using map data or by a GPS device, and a present declination correction value each time the direction of the road is obtained. The declination correction value is automatically updated in such a manner as to decrease the radius of the circle of magnetism.
52 Citations
5 Claims
-
1. A vehicle-direction measuring apparatus for determining the direction of a vehicle in correspondence with a declination correction value by obtaining the direction of the vehicle on the basis of X-Y coordinate data detected by a vehicle-mounted terrestrial magnetism sensor, said apparatus comprising:
-
obtaining means for obtaining the direction of a road on which the vehicle is traveling in correspondence with map data; calculating means for calculating central coordinate data located on a circle of magnetism, said circle having a center representing a true center of magnetism, based on the direction of the road, a present declination correction value, and said X-Y coordinate data detected by said terrestrial magnetism sensor each time the direction of the road is obtained by said obtaining means; correcting means for correcting the declination correction value based on outputs of said calculating means to produce a corrected declination correction value; and means for determining the direction of the vehicle in accordance with an output of said terrestrial magnetism sensor and said corrected declination correction value. - View Dependent Claims (2, 3, 4)
-
-
5. A vehicle-direction measuring apparatus for determining the direction of a vehicle in correspondence with a declination correction value by obtaining the direction of the vehicle on the basis of X-Y coordinate data detected by a vehicle-mounted terrestrial magnetism sensor, said apparatus comprising:
-
obtaining means for obtaining the direction of a road on which the vehicle is traveling in correspondence with GPS data; calculating means for calculating central coordinate data located on a circle of magnetism, said circle having a center representing a true center of magnetism, based on the direction of the road corresponding to the GPS data, a present declination correction value and said X-Y coordinate data detected by said terrestrial magnetism sensor each time the direction of the vehicle corresponding to the GPS data is obtained by said obtaining means; correcting means for correcting the declination correction value based on outputs of said calculating means to produce a corrected declination correction value; and means for determining the direction of the vehicle in accordance with an output of said terrestrial magnetism sensor and said corrected declination correction value.
-
Specification