Optical fiber shape reconstruction method and device based on Beta frame

Abstract

The invention discloses an optical fiber shape reconstruction method based on a Beta frame. The method comprises the following steps: firstly, respectively carrying out bending-free state measurementand bending state measurement on a to-be-measured optical fiber by utilizing a distributed three-dimensional shape sensing system based on an optical frequency domain reflectometer (OFDR), and carrying out cross-correlation demodulation on two groups of signals obtained by measuring whether bending exists or not to obtain a frequency spectrum offset of the whole optical fiber; solving strain values of all positions of the optical fiber by using the spectrum offset, and solving the curvature and the bending angle of the optical fiber by using the relationship between the strain and the curvature and the bending angle; substituting the curvature and the bending angle of the optical fiber into a differential equation of a Beta standard frame to solve the Beta standard frame of each point on the optical fiber; and finally, carrying out tangent vector integration on the curve in the Beta frame to obtain the shape of the optical fiber. According to the method, good curve reconstruction performance can be obtained, and especially when turning point exists in optical fiber bending, reconstruction precision can be obviously improved.

Description

technical field [0001] The invention relates to the field of optical fiber sensing, in particular to a Beta frame-based optical fiber shape reconstruction method and device. Background technique [0002] In recent years, intelligent and flexible structures have been widely used in medical, civil engineering, aerospace, industrial manufacturing and other fields, and their role has continued to deepen. At the same time, the design optimization, structural health monitoring, and adaptive control of these intelligent structures all require accurate measurement and restoration of structural deformation. The development of deformation measurement methods corresponding to this requirement has become a major research hotspot. [0003] Optical fiber shape sensor measures the shape by using multiple strain sensors integrated on the optical fiber to collect data, and then processes the strain data through a specific reconstruction algorithm to reconstruct the shape of the optical fiber...

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Problems solved by technology

[0005] However, there is a problem in the traditional Frenet frame reconstruction method. When there is an inflection point in the reconstructed shape, the main normal vector in the Frenet frame will change suddenly at the inflection point, and there is a discontinuity, so that the tangent vector at this point cannot be obtained correctly. , so that the reconstruction algorithm fails, and the shape after reconstruction cannot be

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