Method, system and device for calibrating a magnetic field sensor

A control device of a magnetic-field sensor for detecting three-axis components of the terrestrial magnetic-field vector, said device comprising:

• a storage unit for holding a reference coordinate point in a predetermined coordinate space obtained by performing coordinate transformation for the three-axis components of the terrestrial magnetic field vector as a reference;
• and
• a computation unit for performing coordinate transformation for the three-axis component output of said magnetic-field sensor occurring when said sensor assumes five or more attitudes to calculate five or more coordinate points in the same coordinate space as with said reference coordinate point, selecting four coordinate points which are as far as possible from one another from among the five or more coordinate points, and creating a sphere on which said selected four coordinate points are positioned,
• wherein said computation unit obtains a magnetic-field offset by calculating the distance between the center of said sphere thus created and said reference coordinate point, and calibrates said magnetic-field sensor using said magnetic-field offset.

A system for calibrating a device containing a three-axis magnetic-field sensor, said system comprising:

• a storage unit for storing a reference coordinate point in a predetermined coordinate space obtained by performing coordinate transformation for the three-axis components of the terrestrial magnetic field vector;
• and
• a computation unit for:
• calculating five or more coordinate points in the same coordinate space as the reference coordinate point by performing coordinate transformation for the three-axis component output of said magnetic-field sensor when said device assumes five or more attitudes;
• selecting four points which are as far as possible from one another from among the five or more coordinate points;
• creating a sphere on which said selected four coordinate points are positioned;
• calculating a magnetic-field offset based on the distance between the center of said sphere thus created and said reference coordinate point;
• and
• calibrating said device based on said magnetic-field offset.