SYSTEM FOR MEASURING A MAGNETIC FILED COMPRISING A THREE-AXIS SENSOR FOR MEASURING A MAGNETIC FILED THAT IS ABLE TO MOVE TOGETHER WITH A CARRIER THAT DISRUPTS THE MEASUREMENTS, AND ASSOCIATED METHOD

• US 20110153233A1
• Filed: 05/14/2009
• Published: 06/23/2011
• Est. Priority Date: 05/14/2008
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation), Movea
• Original Assignee: Commissariat A L'Energie Atomique et AUX Energies Alternatives, Movea
• Inventors: Grenet, Pierre, El-Marfouq, Ismail, Cattin, Viviane
• Granted Patent: US 9,459,098 B2
• Time in Patent Office: Days
• US Class Current: 702/57
• CPC Class Codes: G01C 17/38 Testing, calibrating, or compensating of compasses
• CPC Class Codes: G01R 33/0206 Three-component magnetometers
• CPC Class Codes: G01R 33/025 Compensating stray fields G01R33/0017 takes precedence

Abstract

The magnetic field measurement system comprises a triaxial main sensor (1) for measuring magnetic field that can move jointly with a carrier element (2) capable of generating at least one additional magnetic field disturbing the measurements of said triaxial main sensor (1), said triaxial sensor (1) being adapted for providing orthonormal measurements for a reference magnetic field in the absence of magnetic disturbances due to said carrier element (2). The system comprises means of adjustment (5, 6, 7, 9, 4a, 4b) of said triaxial main sensor (1) comprising a removable additional sensor for magnetic field measurement, that can move jointly with said carrier element (2), and disposed outside said carrier element (2) away from the additional magnetic field or fields.

Claims

1. A triaxial magnetic field measurement system comprising a triaxial main sensor for measuring magnetic field that can move jointly with a carrier element capable of generating at least one additional magnetic field disturbing the measurements of said triaxial main sensor, said triaxial main sensor being adapted for providing orthonormal measurements for a reference magnetic field in the absence of magnetic disturbances due to said carrier element, characterized in that it comprises means of adjustment of said triaxial main sensor comprising means for determining the reference magnetic field, said means for determining the reference magnetic field comprising a predetermined magnetic field generator or a removable additional sensor for magnetic field measurement, that can move jointly with said carrier element, and disposed outside said carrier element away from the additional magnetic field or fields.

2. The system as claimed in claim 1, in which said means of adjustment of said triaxial main sensor comprise means for determining the additional magnetic field or fields generated by said carrier element on the basis of parameters comprising coefficients representative of the magnetic sensitivity of said carrier element, measurements performed by said triaxial main sensor, and temporal variations of these said measurements.

3. The system as claimed in claim 2, in which said means for determining the additional magnetic field or fields generated by said carrier element are adapted for implementing the following system of equations:

4. The system as claimed in claim 1, in which, said means for determining the reference magnetic field comprising a removable additional sensor for magnetic field measurement, said removable additional sensor is a triaxial additional sensor, whose axes are respectively parallel to the axes of the main triaxial sensor.

5. The system as claimed in claim 1, in which, said means for determining the reference magnetic field comprising a removable additional sensor for magnetic field measurement, said removable additional sensor for magnetic field measurement is a scalar sensor.

6. The system as claimed in claim 4, in which said means of adjustment of said triaxial main sensor comprise first calculation means adapted for calculating the respective components of the remanent magnetic field by differences between averages of measurements performed simultaneously by the two triaxial sensors.

7. The system as claimed in claim 6, in which said means of adjustment of said triaxial main sensor comprise second means of calculation of the vectors of said coefficients representative of the magnetic sensitivity of said carrier element by least squares estimation on the following system of equations:

8. The system as claimed in claim 5, in which said means of adjustment of said triaxial main sensor comprise optimization means adapted for optimizing the following equality for a series of measurements performed simultaneously with said triaxial main sensor and said scalar sensor:

∥

Mes_scalar∥

=∥

B_measured−

B_disturbing∥

in which ∥

Mes_scalar∥

represents a norm of a measurement of the scalar sensor, and B_disturbing represents the disturbing additional magnetic field or fields generated by said carrier element.

9. The system as claimed in claim 1, comprising, furthermore, means for correcting the measurements of said triaxial main sensor which are adapted for delivering the real magnetic field on the basis of the magnetic field measured by said triaxial main sensor and data provided by said adjustment means by using the following system of equations:

10. The system as claimed in claim 1, comprising, furthermore, means of predictive correction by consideration of the disturbances of a predictive model, by gradient descent of the additional magnetic field or fields, adapted for using the following relation:

11. A method of triaxial magnetic field measurement by a triaxial main sensor for measuring magnetic field that can move jointly with a carrier element capable of generating at least one additional magnetic field disturbing the measurements of said triaxial main sensor, said triaxial sensor being adapted for providing orthonormal measurements for a reference magnetic field in the absence of magnetic disturbances due to said carrier element, characterized in that said main triaxial sensor is adjusted on the basis of a determination of the reference magnetic field, said determination of the reference magnetic field using a predetermined magnetic field generator or a removable additional sensor for magnetic field measurement, that can move jointly with said carrier element, and disposed outside said carrier element away from the additional magnetic field or fields.

12. The method as claimed in claim 11, in which the additional magnetic field or fields generated by said carrier element is or are determined on the basis of parameters comprising coefficients representative of the magnetic sensitivity of said carrier element, measurements performed by said triaxial main sensor, and temporal variations of these said measurements.

13. The method as claimed in claim 12, in which said determination of the additional magnetic field or fields generated by said carrier element uses the following system of equations: