Pendulum bob-constant section beam fiber bragg grating dip angle sensor and calibration method

Abstract

The invention relates to a pendulum bob-constant section beam fiber bragg grating dip angle sensor. In the sensor, one end of a constant section beam is fixed, and the other end of the constant section beam is connected with a pendulum bob; and two fiber bragg gratings are fixed on two opposite lateral surfaces of the constant section beam respectively. A calibration method comprises the following steps of: changing dip angle of a simply supported beam according to step length delta theta, and recording a center wavelength value lambda i of the sensor at each dip angle point theta I; setting a rectangular coordinate system by taking the dip angle theta as a horizontal coordinate and the difference delta lambda of the change of the center wavelength, which is measured at the corresponding corner actually, of the sensor as a vertical coordinate; and after a discrete distribution graph of delta lambda data points is obtained, performing linear fitting on discrete data points by using a primary polynomial, and calculating beta 1 and lambda according to the principle of a least square method, the essential condition for solving multivariate extreme values and the obtained theta i and lambda i data so as to obtain the fitted delta lambda. The pendulum bob-constant section beam fiber bragg grating dip angle sensor has high measuring accuracy, anti-electromagnetic interference capacity and stability, and is suitable for industrial production and particularly suitable for the monitoring of the structural distortion in civil engineering.

Description

technical field [0001] The invention discloses an optical fiber grating inclination sensor and a calibration method, in particular to a pendulum-equal-section beam optical fiber grating inclination sensor and a calibration method, belonging to the technical field of pressure sensors. technical background [0002] Through the review of domestic and foreign materials, it is found that so far, there are few researches on fiber grating inclination sensors, and they are still in the exploratory stage. [0003] In 2000, Ferdinand and others developed the first fiber Bragg grating inclination sensor by using fiber gratings. Two fiber Bragg gratings are symmetrically stretched between the fixed end and the rotating end. When the structure rotates, the wavelengths of the two gratings are in opposite directions. The direction changes, but the influence of temperature is consistent. Thus, temperature self-compensation is realized. [0004] In 2003, Guan et al. used a bracket, a pendu...

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Problems solved by technology

[0006] In 2005, Dong et al. attached three fiber gratings to three strain beams arranged at 120°. The strain beams were connected to the disk above the pendulum through steel strings. This method not only measures the size of the angle at the same time, but also measures the angle direction, but with less precision

[0007] In 2006, Toshimitsu et al. used a fiber grating connected to a pendulum to make an inclination sensor whose temperature has a great influence

[0008] The existing fiber grating inclination sensor is difficult to be applied to bridge structural deformation monitoring due to the shortcomings of low measurement accuracy, short life, and large volume. Therefore, a new type of pendulum-equal cross-section fiber fiber grating inclination sensor is produced and its calibration method is designed. It is of great significance for the deformation monitoring of civil engineering structures

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