Method of generating geometric heading and positioning system using the same method
A method of generating a geometric heading during positioning is provided. The method includes the following steps: estimating a current declination information of a current position according to a declination database, wherein the declination database gathers a magnetic map and a plurality of declination information corresponding to a difference between a magnetic north and a geometric north at all grid positions on the magnetic map; generating a predicted heading according to an angular velocity reading of a gyroscope and a magnetic heading reading of a magnetometer; and generating the geometric heading according to the current declination information of the current position and the predicted heading.
1. A method of generating a geometric heading during positioning, comprising:
estimating a current declination information of a current position according to a declination database, wherein the declination database gathers a magnetic map and a plurality of declination information corresponding to a difference between a magnetic north and a geometric north at all grid positions on the magnetic map;
generating a current magnetic heading according to a magnetometer;
generating a current geometric heading according to a current angular velocity reading of a gyroscope and a previous geometric heading, wherein the previous geometric heading is generated at a time frame (t−1) and the current geometric heading is generated at a time frame t; and
updating the current geometric heading according to the current declination information of the current position and the current magnetic heading.
2. The method of claim 1 , further comprising:
updating the predicted heading by using a G-sensor, the magnetometer, and the current declination information of the current position so as to generate the geometric heading.
3. The method of claim 1 , further comprises:
generating the current position by using a previous heading and a pedometer or a G-sensor.
4. The method of claim 1 , further comprises:
storing the declination database in a memory.
5. A positioning system for generating a geometric heading, comprising:
an inertial unit, at least comprises a gyroscope for providing a current angular velocity reading and a magnetometer for providing a current magnetic heading reading; and
a processor, arranged for executing the following steps: estimating a current declination information of a current position according to a declination database, wherein the declination database gathers a magnetic map and a plurality of declination information corresponding to a difference between a magnetic north and a geometric north at all positions on the magnetic map; generating a current geometric heading according to the current angular velocity reading of the gyroscope and a previous geometric heading, and updating the current geometric heading according to the current declination information of the current position and the current magnetic heading; wherein the previous geometric heading is generated at a time frame (t−1) and the current geometric heading is generated at a time frame t.
6. The positioning system of claim 5 , wherein the processor is further arranged for executing the following steps:
updating the predicted heading by using a G-sensor, the magnetometer, and the current declination information of the current position so as to generate the geometric heading.
7. The positioning system of claim 5 , wherein the inertial measurement unit further comprises:
a pedometer or a G-sensor, arranged for generating the current position.
8. The positioning system of claim 5 , further comprises:
a memory, arranged for storing the declination database.