BACKGROUND

The present disclosure relates to a cable, a cable shape sensing system, a sensing system including the cable shape sensing system, and a cable shape sensing method.

In the related art, an optical fiber has been used to sense various physical quantities (refer to Japanese Laid-Open Patent Publication No. 2017-032979). Furthermore, there have been disclosed techniques, in recent years, that senses the shape of a multi-core optical fiber in a longitudinal direction by sensing local bending in the longitudinal direction of the multi-core optical fiber (refer to J. P. Moore, “Shape sensing using multi-core fiber”, in Proc. Opt. Fiber Commun. Conf., 2015, p.Th1C.2; J. P. Moore and M. D. Rogge, “Shape sensing using multi-core fiber optic cable and parametric curve solutions”, Opt. Express, vol. 20, no. 3, pp. 2967-2973, 2012; and Paul S. Westbrook, Tristan Kremp, Kenneth S. Feder, Wing Ko, Eric. M. Monberg, Hongchao Wu, Debra A. Simoff, Thierry F. Taunay, and Roy M. Ortiz, “Continuous Multicore Optical Fiber Grating Arrays for Distributed Sensing Applications” J. Lightw. Technol., vol. 35, no. 6, pp. 1248-1252, March 2017).

SUMMARY

There is a need for providing a cable capable of sensing the shape in the longitudinal direction, a cable shape sensing system, a sensing system having the cable shape sensing system, and a cable shape sensing method.

Solution to Problem

According to an embodiment, a cable includes: a plurality of optical fiber cores; and one or more optical fiber core wires including one or more of the optical fiber cores. Further, at least one of the optical fiber core wires is fixed at a plurality of positions in a longitudinal direction of the cable so as to achieve substantially no displacement in a cable radial direction, at least a pair of the optical fiber core wires are fixed in a plane perpendicular to the longitudinal direction of the cable so as to achieve substantially no displacement relative to each other, and sensing of a strain profile in the longitudinal direction of at least the pair of the optical fiber core wires leads to achievement of sensing of a shape of the cable in the longitudinal direction.

