Surface-object identification using ground-buried fibre-optic sensors

Any type of object moving on the ground surface represents a mechanical contact problem. The resulting contact forces cause deformations of the ground, which can be measured using ground buried distributed fibre optic sensors.  By processing the measurements using mechanical inverse analysis, the magnitude and location of contact forces acting on the surface can be identified.

The current research aims to proof this concept in a field experiment where fibre optic sensors are buried in the ground and the ground surface is loaded statically and dynamically. Since the deformations and therefore strains in the ground caused by small surface loads (e.g. pedestrians, animals) are very small, the highly non-linear behaviour of soils at these very small strains has to be taken into account. In this respect fibre optic sensors with their high spatial resolutions and precision provide new insights into the small strain behaviour of soil in non-laboratory environment.

The identification of dynamic surface loads opens a large field of practical applications. This field spreads from perimeter security systems with intrusion detection, to airport and road traffic application as well as biomechanics and sports medicine, where contact forces play an important role in understanding and optimising movement patterns.

PCT/EP2014/001006, (2013), Fibre optic based intrusion sensing system, Inventors: Puzrin A, Friedli B, Hauswirth D

Dr. Balz Friedli