Fiber Bragg grating torque sensor with the adjustable range spoke structure

Abstract

Using the spoke structure as the elastic element, an adjustable range fiber grating torque sensor is designed. Two fiber Bragg gratings with different central wavelengths are symmetrically bonded on the upper and lower surfaces of the elastic plate parallel to the axial direction, respectively, as sensing elements and reference elements. By calibrating the relationship between the torque values and the central wavelength difference between the two reflecting elements, the influence of ambient temperature can be eliminated, and the self compensation function of temperature can be realized. The elastic plate is connected with the inner wheel hub and the outer wheel hub by a bayonet, and is fixed by bolts, and the structure is easy to be disassembled so the range of the sensor can be adjusted by replacing the elastic plate. The dimension of spoke structure is optimized by using the finite element simulation software. The finite element simulation and experimental results show that the strain of the elastic element has a linear relationship with the central wavelength difference of two fiber gratings. When the range is 80 Nm, the average sensitivity of the sensor is 27.1 pm/Nm, the correlation coefficient is 0.997, the repeat ability error is 3.23% FS, and the hysteresis error is 1.03% FS.