AZIMUTH CALCULATION PROGRAM AND ELECTRONIC COMPASS

• US 20090293295A1
• Filed: 08/11/2009
• Published: 12/03/2009
• Est. Priority Date: 03/06/2007
• Status: Active Grant

• Current Assignee: Alps Alpine Co., Ltd.
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Hirobe, Kisei, Yamada, Yukimitsu, Kawarada, Katsuyuki
• Granted Patent: US 8,577,636 B2
• Time in Patent Office: Days
• US Class Current: 33/356
• CPC Class Codes: G01C 17/28 Electromagnetic compasses with north seeking magnetic elements and having electric pick-offs G01C17/26
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G01R 33/0206 Three-component magnetometers

Abstract

An azimuth calculation program is a computer-executable program that performs an azimuth calculation using output of a magnetic sensor. The azimuth calculation program includes a first step of generating one triangle in three-dimensional space using three output values of a magnetic sensor unit, a second step of determining a circumcircle of the triangle, and a third step of performing an azimuth calculation using center coordinates of the circumcircle and output values of the magnetic sensor.

Claims

1. An azimuth calculation program being a computer-executable program performing an azimuth calculation by using output of a magnetic sensor, the azimuth calculation program comprising the steps of:

generating one triangle in three-dimensional space using three output values of the magnetic sensor;

determining a circumcircle of the triangle; and

performing an azimuth calculation using center coordinates of the circumcircle and output values of the magnetic sensor.

2. The azimuth calculation program according to claim 1, wherein when an angle between a plane containing an already determined circumcircle and a plane containing a newly determined circumcircle is within a predetermined range, center coordinates of the already determined circumcircle are used to perform the azimuth calculation.

3. The azimuth calculation program according to claim 1, wherein when an angle between a plane containing an already determined circumcircle and a plane containing a newly determined circumcircle is within a predetermined range, center coordinates of the newly determined circumcircle are used to obtain a weighted average of center coordinates of the already determined circumcircle.

4. The azimuth calculation program according to claim 1, wherein the circumcircle is determined by collecting multiple sets of the three output values, and averaging centers of virtual circumcircles determined from the respective sets of the three output values.

5. An electronic compass comprising:

a compass module having a magnetic sensor; and

control means having the azimuth calculation program of claim 1, the azimuth calculation program performing an azimuth calculation using output of the magnetic sensor.

6. The electronic compass according to claim 5, wherein the control means includes a plurality of buffers capable of storing the three output values, and determines, on the basis of a predetermined condition, whether the output of the magnetic sensor can be stored in the plurality of buffers.