Remote vibration sensing through opaque media using permanent magnets
A method of sensing vibrations or displacements remotely is provided. Magnets are attached to vibrating objects or the vibrating objects themselves are magnetic. A number of magnetic sensors are placed a specified distance from the magnets. Vibrational displacement of the vibrating objects is determined according to a model that maps changes in magnetic field to vibrations or spatial displacements.
1. A method of sensing vibrations or displacements remotely, comprising:
attaching a number of magnets to a number of vibrating objects;
placing a number of magnetic field sensors a specified distance from the number of magnets;
detecting, by the number of magnetic field sensors, changes in a magnetic field;
determining, by a number of processors, vibrational displacement of the number of vibrating objects according to a model that maps changes in the magnetic field to vibrations or spatial displacement; and
detecting a damage or a degradation to an object in the number of vibrating objects by detecting shifts in a natural frequency and changes in mode shapes of the number of vibrating objects.
2. The method of claim 1 , wherein the number of magnets comprise at least one of:
permanent magnets;
ferromagnets;
paramagnets.
3. The method of claim 1 , further comprising deriving the model via one of the follow ways:
directly from first principles;
simplified from a first principles model; or
fitted from a first principles model.
4. The method of claim 3 , wherein the first principles comprise a dipole model.
5. The method of claim 1 , wherein the model is a single or multiple degree-of-freedom calibrated local model created by mapping displacements of the number of magnets with changes in the magnetic field.
6. The method of claim 1 , wherein the vibrations or spatial displacement are determined from the model via single or multiple degree-of-freedom linear or nonlinear inversion techniques.
7. The method of claim 1 , wherein the number of magnetic field sensors comprise three-axis magnetic field sensors.
8. The method of claim 1 , wherein multiple magnets are attached to a single vibrating object.
9. The method of claim 1 , wherein multiple magnets are attached to multiple vibrating objects.
10. The method of claim 1 , wherein the number of magnets and vibrating objects are located inside a vessel, and the number of magnetic field sensors are located outside the vessel, wherein the vessel is magnetically transparent.
11. The method of claim 10 , wherein the vessel is optically opaque.
12. A method of remotely sensing vibrations or displacements, the method comprising:
positioning a number of magnetic vibrating objects;
placing a number of magnetic field sensors a specified distance from the number of magnetic vibrating objects;
detecting, by the number of magnetic field sensors, changes in a magnetic field;
determining, by a number of processors, a vibrational displacement of the number of magnetic vibrating objects according to a model mapping changes in the magnetic field to the vibrations or displacements; and
detecting a damage or a degradation to an object in the number of magnetic vibrating objects by detecting shifts in a natural frequency and changes in mode shapes of the number of magnetic vibrating objects.
13. The method of claim 12 , wherein the number of magnetic vibrating objects are at least one of:
permanents magnets;
ferromagnetic;
paramagnetic.
14. The method of claim 12 , further comprising deriving the model in one of the follow ways:
directly from first principles;
simplified from first a first principles model; or
fitted from a first principles model.
15. The method of claim 14 , wherein the first principles comprise a dipole model.
16. The method of claim 12 , wherein the model is a single or multiple degree-of-freedom calibrated local model created by mapping displacements of ferromagnetic or paramagnetic objects with changes in the magnetic field.
17. The method of claim 12 , wherein the vibrations or displacements are determined from the model via single or multiple degree-of-freedom linear or nonlinear inversion techniques.
18. The method of claim 12 , wherein the number of magnetic field sensors are three-axis magnetic field sensors.
19. The method of claim 12 , wherein the number of magnetic vibrating objects are located inside a vessel, and the number of magnetic field sensors are located outside the vessel, wherein the vessel is magnetically transparent.
20. A method of remotely sensing vibrations or displacements, the method comprising:
positioning a number of magnetic vibrating objects inside a vessel that is optically opaque and magnetically transparent;
placing a number of magnetic field sensors outside the vessel a specified distance from the number of magnetic vibrating objects;
detecting, by the number of magnetic field sensors, changes in a magnetic field;
determining, by a number of processors, a vibrational displacement of the number of magnetic vibrating objects according to a model mapping changes in the magnetic field to the vibrations or displacements.