3D beam shape estimation based on distributed coaxial cable interferometric sensor

Abstract

We present a coaxial cable interferometer based distributed sensing system for 3D beam shape estimation. By making a series of reflectors on a coaxial cable, multiple Fabry-Perot cavities are created on it. Two cables are mounted on the beam at proper locations, and a vector network analyzer (VNA) is connected to them to obtain the complex reflection signal, which is used to calculate the strain distribution of the beam in horizontal and vertical planes. With 6 GHz swept bandwidth on the VNA, the spatial resolution for distributed strain measurement is 0.1 m, and the sensitivity is 3.768 MHz mε −1 at the interferogram dip near 3.3 GHz. Using displacementstrain transformation, the shape of the beam is reconstructed. With only two modified cables and a VNA, this system is easy to implement and manage. Comparing to optical fiber based sensor systems, the coaxial cable sensors have the advantage of large strain and robustness, making this system suitable for structure health monitoring applications.

3D small strain large deflection beam shape sensing including poisson effect

“…In these works, the hypothesis concerning the beam The Euler-Bernoulli beam theory makes the assumption the cross section remains rigid and perpendicular to the neutral axis. Different beam shape monitoring methods based on this hypothesis have been proposed over the years [42,10,13,16,22,31,45,50,36] with applications such as bridge monitoring [9,11,39,47], minimally-invasive surgery [1,33,32,38,18,26,30,43,49,37] or wing deformation [23]. In these methods, the bending informations of the beam are retrieved from the measures of the strain sensors placed parallel to the beam at its surface and are used to reconstruct the beam shape in 2D or 3D.…”

Strain Gauges Based 3D Shape Monitoring of Beam Structures Using Finite Width Gauge Model

“…The topic of using strain measures for beam shape monitoring has been widely covered in the litterature on both theoretical [10,11,12,13,14] and applied aspects, such as needles deflections during medical intervention [4,5,15] or bridge deformation over time [16]. The strain measures are acquired through technologies such as strain gauges [10,13,17], or fiber Bragg gratings [16,18,19,20,21] and are used to obtain deformations of the beam.…”

“…The strain measures are thus used as inputs in a reconstruction method to obtain the structure deformed shape. The reconstruction methods proposed in the literature are either two dimensional [10,11,16,17,18,23] or three dimensional [12,14,19,20,21] depending on the deformation hypothesis made.…”

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

“…Coaxial cable sensors have a similar working principle, but are more robust than their fiber optic counterparts as the material is usually based on polymers that can withstand large strain. Thus, coaxial cable sensors are suitable for heavy-duty and large-strain applications such as structural health monitoring [3,4].…”