Patent ID: 7865323

Claim:
A calibration method that is executed by a computer for finding a reference point for the output of a magnetic sensor, comprising: obtaining at least four outputs from the magnetic sensor wherein at least one output contains an error; forming at least two triangles from said at least four outputs of the magnetic sensor in a three-dimensional space, the at least two triangles including a first triangle and a second triangle; finding a first circle circumscribing the first triangle and a second circle circumscribing the second triangle, the first circle and the second circle each corresponding to a cut section of a virtual sphere; obtaining a first normal vector and a second normal vector passing through a center of the first circle and a center of the second circle, respectively; finding the reference point as an intersection of the first and second normal vectors, the reference point being the center of the virtual sphere; and calibrating the magnetic sensor using the reference point, wherein said finding the reference point includes: acquiring a plurality of sets of said at least four outputs, wherein each set defines the corresponding virtual sphere; and finding an average of a group of centers, each center being found on the basis of the corresponding set of said at least four outputs.