An FBG-Sensing Two-Dimensional Vibration Sensor Based on Multi-Axis Flexure Hinge

Based on the unique advantages of fiber Bragg (FBG) in the field of vibration monitoring, a 2-D FBG accelerometer based on multi-axis flexure hinge is proposed. With the adoption of symmetrical multi-axis flexure hinges, the sensing probe has the same sensitivity in two measuring directions. The differential arrangement of the two couple FBGs can eliminate the influence of temperature, and in addition, its sensitivity is twice that of single FBG. The structure and principle of the sensor are explained, and its acceleration sensitivity and resonance frequency are analyzed theoretically in this paper. On this basis, the simulation analysis is carried out and two kinds of sensors for different occasions are made finally. Experimental studies show that the sensors can pick up the vibration signal accurately and have preferably temperature self-compensation effect under the condition form 20 °C to 90 °C. The stable frequency band of the max-sensor is 5 to 170 Hz, the acceleration sensitivity is up to 220 pm/g, the cross-interference in two measuring directions is not exceeding 4%, and the resonant frequency is 279.2 Hz. The min-sensor has a wide flat range from 20 to 600 Hz with an acceleration sensitivity of 40 pm/g. Its cross-interference is less than 3.5%, and the resonant frequency is 814.3 Hz.