Calibration program and electronic compass
First Claim
1. 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.
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Accused Products
Abstract
The object of the present invention is to provide a calibration program and an electronic compass that make it possible to calibrate the output of a magnetic sensor with a small amount of computation while a user does not notice the execution of calibration. A calibration program according to an aspect of the invention includes: a step of forming at least two triangles 21 and 22 with the use of at least four outputs of a magnetic sensor in a three-dimensional space; a step of finding circles 23 and 24 circumscribed about the triangle 21 and 22, respectively; and a step of finding the intersection of normal vectors 25 and 26 each of which passes through the center of the corresponding circumscribed circle so as to find a reference point.
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Citations
9 Claims
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1. A calibration method that is executed by a computer for finding a reference point for the output of a magnetic sensor, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A calibration method that is executed by a computer for finding a reference point for the output of a magnetic sensor, comprising:
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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; finding, for each of said at least two triangles, a circle circumscribed about the triangle, each circle corresponding to a cut section of a virtual sphere; and finding an intersection of normal vectors each of which passes through a center of the corresponding circumscribed circle so as to find the reference point, 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, and wherein said at least four outputs are obtained so as to satisfy following two conditions;
a first condition is that each distance between a point of one output and a point of another output is not smaller than a predetermined distance value; and
a second condition is that a planed angle or each planed angle that is formed by said at least two triangles does not exceed a predetermined angle tolerance (Δ
θ
), the center of which is 90°
. - View Dependent Claims (9)
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Specification