Distributed fiber-optic sensing systems, devices, and methods
A distributed fiber optic sensing (DFOS) system and method record optical data in one or more optical fibers, calculate physical parameters from the recorded optical data, and compute locations of vehicles passing above or beside the one or more optical fibers based on the DFOS data. A method of determining a force exerted by an object onto a surface under the object using at least one optical fiber located below or adjacent to the surface includes measuring DFOS data arising from strain in the at least one optical fiber responsive to the force, determining at least one relationship between the measured DFOS data and the force and processing the measured DFOS data and the at least one relationship to determine the force.
1 . A method of determining a force exerted by an object onto a surface under the object using at least one optical fiber located below or adjacent to the surface, the method including:
measuring distributed fiber-optic sensing (DFOS) data arising from strain in the at least one optical fiber responsive to the force;
determining at least one relationship between the measured DFOS data and the force, wherein the at least one relationship corresponds to at least one transfer function of a medium between at least one location on the surface and at least one sensing segment on the at least one optical fiber; and
processing the measured DFOS data and the at least one relationship to determine a force distribution including magnitude and location of the force.
2 . The method of claim 1 , further including deriving object information of the object based on the force distribution.
3 . The method of claim 2 , wherein the object information includes at least one of a footprint area of the object and a mass distribution of the object.
4 . The method of claim 2 , wherein the object information includes at least one of a velocity of the object, an acceleration of the object, a momentum of the object, a speed of the object, an identity of the object and a travelling direction of the object.
5 . The method of claim 1 , wherein the at least one relationship between the measured DFOS data and the force is determined by training a machine learning network using at least one of the DFOS data and a physical relationship between DFOS measurements and force distribution.
6 . The method of claim 1 , wherein the at least one location on the surface includes multiple locations corresponding to a mesh or matrix of nodes on the surface.
7 . The method of claim 6 , wherein the DFOS data and the at least one transfer function are used to determine the force distribution at specific locations within the mesh of nodes over the at least one sensing segment on the at least one optical fiber.
8 . The method of claim 1 , wherein determining the force distribution includes using at least one statistical optimization method and inverting a matrix related to the at least one transfer function, wherein inverting the matrix related to the at least one transfer function is performed before performing DFOS.
9 . The method of claim 8 , wherein the at least one statistical optimization method is conducted in real-time while performing DFOS.
10 . The method of claim 1 , wherein determining the at least one transfer function of the medium between at least one location on the surface and at least one sensing segment on the at least one optical fiber is based on at least two of material of the medium, geometry of the at least one optical fiber relative to the at least one location on the surface, and local geological information.
11 . The method of claim 1 , further including selecting at least one gauge length of the at least one optical fiber for performing DFOS, the gauge length corresponding to the at least one sensing segment on the at least one optical fiber.
12 . The method of claim 1 , wherein the object includes a vehicle.
13 . The method of claim 12 , wherein object information of the object includes at least one of a count of axles of the vehicle and occupancy of the vehicle.
14 . The method of claim 1 , wherein the surface includes multiple lanes.
15 . The method of claim 14 , further including determining lane quantization of the multiple lanes.
16 . A method of determining a force exerted by an object onto a surface under the object, the method comprising:
measuring DFOS data arising from strain in an optical fiber located below or adjacent to the surface; and
calculating a force magnitude at one or more locations on the surface based on the measured DFOS data and at least one transfer function of a medium between at least one location on the surface and at least one sensing segment on the optical fiber.
17 . The method according to claim 16 , further comprising determining at least one relationship between the DFOS data and the force magnitude wherein the relationship corresponds to the at least one transfer function of the medium between the at least one location on the surface and the at least one sensing segment of the optical fiber.
18 . The method according to claim 16 , wherein the measuring the DFOS data includes measuring ground motion.
19 . The method according to claim 16 , further comprising:
generating an alert in response to the calculating of the force.