Method of generating geometric heading and positioning system using the same method

• US 9,097,533 B2
• Filed: 01/11/2013
• Issued: 08/04/2015
• Est. Priority Date: 01/12/2012
• Status: Active Grant

• Current Assignee: China Mobile Hong Kong Company Limited (China Mobile Limited)
• Original Assignee: CyWee Group Ltd.
• Inventors: Ye, Zhou, Liou, Shun-Nan, Lee, Chin-Lung
• Primary Examiner(s): Cheung, Mary
• Assistant Examiner(s): Trivedi, Atul
• Application Number:
  US13/739,089
• Publication Number:
  US 20130184991A1
• Time in Patent Office: 935 Days
• Field of Search: 701/504, 701/507, 701522-525, 701/530
• US Class Current: 1/1
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G01C 21/08 involving use of the magnetic field of the earth

Abstract

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.

Claims

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.