面向低频振动测量的双光纤光栅加速度传感器研究

Research on double fiber grating acceleration sensor for low frequency vibration measurement

低频振动测量对地震海啸等灾害预警、地质勘探和能源开发等领域具有重要意义。针对现有FBG加速度传感器测量低频振动时灵敏度较低的问题,提出一种高灵敏度低频双FBG加速度传感器。采用十字簧片作为拾振结构,理论分析传感器的振动响应特性,给出传感器的谐振频率和灵敏度公式。建立传感单元的数学模型,对传感单元结构参数进行优化,并利用有限元仿真验证理论分析结果,最后制作传感器实物并对其进行性能测试。结果表明,传感器固有频率为65 Hz,在3~45 Hz频段具有平坦的灵敏度响应,动态范围为73 dB@10 Hz,灵敏度为1498.29 pm/g,线性度为0.9998,横向串扰为–33.99 dB,能够满足工程中低频振动检测的要求。

The measurement of low-frequency vibration is of great significance in seismic monitoring,health monitoring of large and medium-sized engineering structures,resource exploration,etc.In view of the low sensitivity of FBG acceleration sensors in measuring low-frequency vibration,a high sensitivity low frequency dual FBG accelerometer is proposed.Using the cross reed as the picking structure,the vibration response characteristics of the sensor are analyzed theoretically,and the resonant frequency and sensitivity formulas of the sensor are given.The mathematical model of the sensor unit is established,the structural parameters of the sensor unit are optimized,and the theoretical analysis results are verified by finite element simulation.Finally,the physical sensor is made and its performance is tested.The results suggested that the natural frequency of the acceleration sensor was 65 Hz,and it gave a flat sensitivity response in the low frequency band of 3-45 Hz,the dynamic range was 73 dB@10 Hz,the acceleration sensitivity being 1498.29pm/g,and the linearity r2 being 0.9998,and the transverse crosstalk in the working frequency band was–33.99 dB,so the designed sensor is suitable for low-frequency and medium-frequency vibration detection in engineering.