Design and investigation of a novel vector displacement sensor using fiber Bragg grating technology.

• A novel FBG-based sensor for vector displacement measurement has been presented. • The sensor shows high linearity with the R2 of 0.998, large measurement range of 140 mm, high sensitivity of 4.362 pm/mm, maximum hysteresis error of 3.25% and maximum repeatability error of 6.62%, respectively. • A series of sensor calibrations and performance tests of the sensor are conducted. This paper presents a novel fiber Bragg grating (FBG)-based displacement sensor with simple construction for vector deformation monitoring of slope surface. The interesting structure design and sensing principle of determining the displacement direction and amplitude simultaneously are reported. Calibration tests of six different auxiliary structures (namely core sensing elements) of the sensor are reported, which demonstrates that they are characterized by a superb linearity with an R2 of over 0.998, large measurement range of 140 mm, high sensitivity of 4.362 pm/mm, maximum hysteresis error of 3.25% and maximum repeatability error of 6.62%, respectively. A simulated rock slope test of the sensor is conducted to investigate the performance for determining the progressive sliding process of sliding mass. Additionally, a homogeneous soil slope model test is further conducted and the vector deformation of slope surface is accurately captured by three proposed FBG-based displacement sensors. This capability in identifying two-dimensional displacement can provide a bright application prospect in intelligent monitoring field. [ABSTRACT FROM AUTHOR]