Method and a device for determining a direction in a magnetic field
First Claim
1. A method for determining the direction of a magnetic field, the method comprising:
- measuring with a portable electronic compass device three field vectors of a magnetic field a desired number of times,forming from each measurement a data point in a three-dimensional co-ordinate system,calculating a common reference point for the measured data points,determining the location of the device relative to the reference point in the co-ordinate system,comparing the co-ordinates of the reference point obtained to the co-ordinates of at least one previous reference point,calibrating the co-ordinate values of the reference point, andindicating the direction of the magnetic field with the aid of the reference point,wherein the data points are formed on an essentially spherical surface and the calculated reference point is the centre point of the sphere, andwherein the reference point is calculated by forming three line segments between selected data points, from which unit vectors are formed for three planes passing through the centre points of the segments, the intersection point of the planes being the reference point.
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Abstract
A method and an electronic device for determining the direction of a magnetic field, in which a mobile electronic compass device is used to measure three field vectors of the magnetic field the desired number of times. From each measurement, a data point (p1-p6) is formed in a three-dimensional co-ordinate system, for which measured data points a common reference point (C) is calculated. The location of the device is determined relative to the reference point in said co-ordinate system and the co-ordinates of the reference point obtained are compared to the co-ordinates of at least one previous reference point, and the co-ordinate values of the reference point are calibrated, after which the direction of the magnetic field is indicated with the aid of the reference point.
19 Citations
19 Claims
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1. A method for determining the direction of a magnetic field, the method comprising:
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measuring with a portable electronic compass device three field vectors of a magnetic field a desired number of times, forming from each measurement a data point in a three-dimensional co-ordinate system, calculating a common reference point for the measured data points, determining the location of the device relative to the reference point in the co-ordinate system, comparing the co-ordinates of the reference point obtained to the co-ordinates of at least one previous reference point, calibrating the co-ordinate values of the reference point, and indicating the direction of the magnetic field with the aid of the reference point, wherein the data points are formed on an essentially spherical surface and the calculated reference point is the centre point of the sphere, and wherein the reference point is calculated by forming three line segments between selected data points, from which unit vectors are formed for three planes passing through the centre points of the segments, the intersection point of the planes being the reference point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An electronic device for determining the direction of a magnetic field, comprising:
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at least one electromagnetic sensor configured to produce signals representing measurements of at least three field components of the magnetic field, and the direction of the magnetic field; a memory; and a processing unit operably coupled to the memory and to the at least one sensor, the processing unit adapted; to form from each measurement a data point in a three-dimensional co-ordinate system, to calculate a common reference point for a number of data points produced by several measurements, to compare the co-ordinates of the calculated reference point with the value of the co-ordinates of at least one previous reference point, to calibrate on the basis of the comparison the location of the device relative to the reference point in the co-ordinate system, and to produce an indication of the direction of the magnetic field relative to the device with the aid of the reference point, wherein the data points are arranged to be formed on an essentially spherical surface, whereby the common reference point obtained by calculation is the centre point of the sphere, the processing unit being adapted to calculate the reference point by forming three line segments between selected data points, from which unit vectors are formed to three planes passing through the centre points of the segments, whereby the intersection point of the planes is the reference point. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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Specification