Distributed torsion sensor based on cascaded coaxial cable Fabry–Perot interferometers

Abstract

Cascaded coaxial cable Fabry–Perot interferometers (FPI) are studied and demonstrated for distributed torsion measurement. Multiple weak reflectors are implemented on a coaxial cable so that any two consecutive reflectors can form a Fabry–Perot cavity. By fixing the cable sensor in a helical form on a shaft, the distributed torsion of the shaft can be measured by the cascaded Fabry–Perot cavities. A test on a single section shows that the sensor has a linear response with a sensitivity of 1.834 MHz (rad/m)−1 in the range of twisted rate from 0 to 8.726 rad m−1. The distributed torsion sensing capability is useful in drilling process monitoring, structure health monitoring and machine failure detection.

Fiber-Optic Sensors for Measurements of Torsion, Twist and Rotation: A Review

“…Similar results can be achieved by specially designed measurements bodies as, for example, reported in [112]. Another interesting approach is a distributed torsion sensor employing cascaded coaxial cable Faby-Perot interferometers mounted on a shaft, where the authors have implemented weak reflectors on a coaxial cable, thus forming between any two consecutive reflectors a Fabry-Perot cavity [113]. Torsion is measured indirectly from the measured axial strain due to applied torsion to the shaft.…”

A Novel Smart CFRP Cable Based on Optical Electrical Co-Sensing for Full-Process Prestress Monitoring of Structures

“…Coaxial cables with high elongation (strain up to 15%, more than steel yield deformation) have a similar electromagnetic (EM) theory to optical fiber except for the frequency of the electromagnetic waves that travel within them, which has been greatly developed in recent years. A series of coaxial cable-based sensors have been developed, including coaxial cable Bragg gratings (CCBGs) [29][30][31][32], long-period Bragg gratings (LPBGs) [33], and coaxial cable Fabry-Perot interferometer (CCFPI) [34][35][36]. CCFPI sensor has the advantages of small spatial resolution and adjustable gauge length, which is superior to other coaxial cable sensors.…”

Distributed temperature sensing with unmodified coaxial cable based on random reflections in TDR signal

“…Time domain reflectometry (TDR) has been developed as a distributed sensing method [5][6][7][8] for fault location and other applications since the 1970s [9][10][11][12][13]. Recently, coaxial cable sensors based on Fabry-Perot interferometers (FPIs) and coaxial cable Bragg gratings (CCBGs) have been reported [14][15][16][17][18]. These will bring more measurement accuracy into the family of coaxial cable sensors compared to traditional TDR methods.…”