High-accuracy fiber Bragg grating inclinometer

Abstract

Inclination monitoring plays a significant role in research on deformation monitoring of slopes, inclination monitoring of bridges, earthquake monitoring, and other areas of monitoring. Existing electromagnetic signal-based inclinometers face practical issues such as difficulty adapting to harsh environments, poor large-scale networking capabilities, and unstable signal transmission. Hence, what we believe to be a novel inclinometer based on fiber sensing principles is proposed. The sensor employs suspension sensing based on the plumb principle, using bearings to overcome mechanical friction caused by rigid fixation between the mass block and the cantilever, thereby improving sensitivity and accuracy of the sensor. Key structural parameters of the sensor were optimized and simulated, followed by fabrication of the sensor and performance test on an inclination test platform. Experimental results indicate that, within a measurement range of ±9∘, the sensor exhibited a sensitivity of 305.2 pm/°, a resolution of approximately 3.3×10−4∘, an accuracy of 2%, a repeatability error of 1.9%, and favorable creep resistance stability for long-term measurement, thus addressing the requirements for slope deformation monitoring.