Method for locating at least one movable magnetic object and associated system

1. A method for locating at least one movable magnetic object with respect to an array of at least N triaxial magnetometers that are mechanically connected to one another with no degree of freedom in order to preserve a known relative position of these magnetometers, N being an integer at least equal to 2, comprising steps consisting in:

loading the measurements of the magnetometers, at a current time;

calculating a weighted average of said measurements of the magnetometers representing an average terrestrial magnetic field and an average magnetic field due to the movable magnetic object(s);

subtracting said weighted average from each of said measurements in order to obtain modified measurements;

loading said modified measurements and a location of the one or more movable magnetic objects at the current time as input into a filtering operation for locating the one or more movable magnetic objects;

implementing the location filtering operation, this comprising steps consisting in:

calculating a weighted average of estimations of data delivered by said magnetometers;

subtracting said weighted average from each of said estimated data; and

delivering as output a location of the one or more movable magnetic objects at a subsequent time.

2. The method as claimed in claim 1 , wherein said weighted average uses weighting coefficients that are identical for each of the N magnetometers.

3. The method as claimed in claim 1 , wherein said weighted average uses weighting coefficients that are lower for P magnetometers, among the N magnetometers, closest the one or more movable magnetic objects, P being an integer lower than N.

4. The method as claimed in claim 3 , wherein said weighted average uses zero weighting coefficients for said P magnetometers.

5. The method as claimed in claim 1 , wherein said weighted average uses zero weighting coefficients except for the magnetometer, among the N magnetometers, furthest from the one or more movable magnetic objects.

6. A system for locating at least one movable magnetic object comprising:

an array of at least N triaxial magnetometers that are mechanically connected to one another with no degree of freedom in order to preserve a known relative position of these magnetometers, N being an integer at least equal to 2;

an electronic processing unit suitable for determining the location of the one or more movable magnetic objects from measurements delivered by the magnetometers of the array and a location filter;

said electronic processing unit comprising:

means for loading measurements of the magnetometers, at a current time;

means for calculating a weighted average of said measurements of the magnetometers representing an average terrestrial magnetic field and an average magnetic field due to the movable magnetic object(s); and

means for subtracting said weighted average from each of said measurements in order to obtain modified measurements;

the location filter FL) comprising:

means for loading said modified measurements and a location of the one or more movable magnetic objects at the current time as input into a filtering operation for locating the movable magnetic object;

means for calculating a weighted average of estimations of data delivered by said magnetometers;

means for subtracting said weighted average from each of said estimated data; and

means for delivering as output a location of the one or more movable magnetic objects at a subsequent time.