Two-Dimensional Inclinometer Based on an Elastic Cylinder Cantilever and Eight FBGs

A two-dimensional (2-D) fibre Bragg grating (FBG) inclinometer with the ability to measure the inclination and azimuth angle was investigated herein. Its design involved pasting eight FBGs on an elastic cylinder cantilever (ECC). Based on derivations of formulae and finite element simulations, the dependence of the wavelength shift of FBGs on inclination and azimuth angles was established using the bending and tensile strains of the ECC. A series of sensing tests were conducted using a homemade inclination–azimuth test system to ascertain the sensor performance of the 2-D FBG inclinometer; good consistency was observed between theoretical and experimental data. The average sensitivity of the inclination angle was 6.73 pm/° – in the range of 0° to 90° – and the average sensitivity of the azimuth angle was 9.22 pm/° in the angle range of 0 to 360°.