Magnetic sensor system

Patent metadata

Field	Value
Publication number	US-9864019-B2
Application number	US-201313903421-A
Country	US
Kind code	B2
Filing date	May 28, 2013
Priority date	Oct 24, 2012
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

Magnetic sensor system including an assembly comprising first, second, and third scalar point-sensor magnetometers being fixedly mounted with respect to one another such that the position of each magnetometer's axis is invariable with respect to the other magnetometers' axes. When the sensor assembly is in operation, each magnetometer's axis forms an angle with ambient magnetic field lines. Each magnetometer has an operating range defined with respect to a range of values of the angle formed by its axis and the ambient magnetic field. The magnetometers are positioned such that at least one of magnetometers is within its operating range at any point in time. Each magnetometer has an output signal. Computer processor determines which of the output signals is to be used any particular point in time in the sensing of local variations in the ambient magnetic field. Method of operation of the magnetic sensor system/assembly is disclosed.

First claim

The invention claimed is:

1. A magnetic sensor system suitable for sensing local variations in an ambient magnetic field caused by a mass of ferromagnetic material, the sensor system comprising:
a magnetic sensor assembly, including;
a first scalar point-sensor magnetometer, the first scalar point-sensor magnetometer having a first scalar magnetometer axis;
a second scalar point-sensor magnetometer, the second scalar point-sensor magnetometer having a second scalar magnetometer axis;
a third scalar point-sensor magnetometer, the third scalar point-sensor magnetometer having a third scalar magnetometer axis;
the first scalar point-sensor magnetometer, the second scalar point-sensor magnetometer, and the third scalar point-sensor magnetometer being fixedly mounted with respect to one another such that (i) the position of each of the scalar magnetometer axes is invariable with respect to the other scalar magnetometer axes, and (ii) when the magnetic sensor assembly is in operation, at any particular point in time,
the first scalar magnetometer axis forms a first angle with magnetic field lines of the ambient magnetic field at a location of the magnetic sensor assembly in a first plane defined by the first scalar magnetometer axis and the magnetic field lines,
the second scalar magnetometer axis forms a second angle with the magnetic field lines of the ambient magnetic field at the location of the magnetic sensor assembly in a second plane defined by the second scalar magnetometer axis and the magnetic field lines,
the third scalar magnetometer axis forms a third angle with the magnetic field lines of the ambient magnetic field at the location of the magnetic sensor assembly in a third plane defined by the third scalar magnetometer axis and the magnetic field lines,
the first scalar magnetometer axis intersects a plane parallel to both the second scalar magnetometer axis and the third scalar magnetometer axis at a fourth angle,
the second scalar magnetometer axis intersects a plane parallel to both the first scalar magnetometer axis and the third scalar magnetometer axis at a fifth angle, and
the third scalar magnetometer axis intersects a plane parallel to both the first scalar magnetometer axis and the second scalar magnetometer axis at a sixth angle; and

the first scalar point-sensor magnetometer having a first scalar magnetometer operating range defined with respect to a range of values of the first angle, the second scalar point-sensor magnetometer having a second scalar magnetometer operating range defined with respect to a range of values of the second angle, the third scalar point-sensor magnetometer having a third scalar magnetometer operating range defined with respect to a range of values of the third angle;
the first scalar point-sensor magnetometer, the second scalar point-sensor magnetometer, and the third scalar point-sensor magnetometer positioned with respect to one another such that, at the particular point in time, at least one of: the first angle is within the first scalar magnetometer operating range, the second angle is within the second scalar magnetometer operating range, and the third angle is within the third scalar magnetometer operating range; and

a non-transient computer-readable information storage medium storing program instructions that when executed by a computer processor determine which of a first output from the first scalar point-sensor magnetometer, a second output from the second scalar point-sensor magnetometer, and a third output from a third scalar point-sensor magnetometer is to be used at the particular point in time in the sensing of local variations in the ambient magnetic field.

2. The magnetic sensor system of claim 1 , wherein the first output from the first scalar point-sensor magnetometer is a first output signal, the second output from the second scalar point-sensor magnetometer is a second output signal, the third output from the third scalar point-sensor magnetometer is a third output signal; and the magnetic sensor system further comprising:
at least one frequency-to-digital converter converting the first output signal to a first digital output signal, the second output signal to a second digital output signal, and the third output signal to a third digital output signal;
the computer processor, the computer processor being in communication with the at least one frequency-to-digital converter to receive the digital output signals therefrom.

3. The magnetic sensor system of claim 1 , wherein the non-transient computer-readable information storage medium stores program instructions that when executed by the computer processor determine which of the first output signal, the second output signal, and the third output signal is to be used at the particular point in time in the sensing of local variations in the ambient magnetic field based, at least in part, on which of the scalar point-sensor magnetometers has its angle within its operating range at the particular point in time.

4. The magnetic sensor system of claim 3 , wherein, at the particular point in time, more than one of the scalar point-sensor magnetometers has its angle within its operating range.

5. The magnetic sensor system of claim 1 , wherein the non-transient computer-readable information storage medium stores program instructions that when executed by the computer processor determine which of the first output signal, the second output signal, and the third output signal is to be used at the particular point in time in the sensing of local variations in the ambient magnetic field based, at least in part, on a strength of the scalar magnetometer output signals.

6. The magnetic sensor system of claim 1 , wherein the non-transient computer-readable information storage medium stores program instructions that when executed by the computer processor determine which of the first output signal, the second output signal, and the third output signal is to be used at the particular point in time in the sensing of local variations in the ambient magnetic field based, at least in part, on which one of the output signals was being used immediately prior to the particular point in time.

7. The magnetic sensor system of claim 1 , wherein the first scalar point-sensor magnetometer, the second scalar point-sensor magnetometer, and the third scalar point-sensor magnetometer are positioned one with respect to another to form a pyramidal structure.

8. The magnetic sensor system of claim 1 , wherein the first scalar magnetometer, the second scalar magnetometer, and the third scalar magnetometer are positioned in-line with respect to one another.

9. The magnetic sensor system of claim 1 , wherein
the fourth angle is between 35° and 55° (inclusive), or between 125° and 145° (inclusive), or between 215° and 235° (inclusive), or between 305° and 325° (inclusive);
the fifth angle is between 35° and 55° (inclusive), or between 125° and 145° (inclusive), or between 215° and 235° (inclusive), or between 305° and 325° (inclusive); and
the sixth angle is between 35° and 55° (inclusive), or between 125° and 145° (inclusive), or between 215° and 235° (inclusive), or between 305° and 325° (inclusive).

10. The magnetic sensor system of claim 1 , wherein the first scalar magnetometer operating range is between 10° and 80° (inclusive) and between 100° and 170° (inclusive); the second scalar magnetometer operating range is between 10° and 80° (inclusive) and between 100° and 170° (inclusive); and the third scalar magnetometer operating range is between 10° and 80° (inclusive) and between 100° and 170° (inclusive).

11. The magnetic sensor system of claim 1 , wherein each of the scalar point-sensor magnetometers is

Assignees

• Cae Inc

Inventors

• Lortie Francis

Classifications

• G01R33/02 Primary

  Measuring direction or magnitude of magnetic fields or magnetic flux (G01R33/20 takes precedence) · CPC title

• G01R33/028 Primary

  Electrodynamic magnetometers · CPC title