基于FBG的悬臂梁式微力与微位移传感单元

Cantilever beam type micro-force and micro-displacement sensing unit based on fiber Bragg grating

设计了一种基于光纤布拉格光栅(fiber Bragg grating,FBG)的微力与微位移双物理量传感单元,采用矩形悬臂梁型弹性体结构以及两片FBG布片方式,提高了力和位移灵敏度,实现了温度补偿,位移灵敏度可通过改变悬臂梁的固定位置和长度进行调整。对传感单元的性能进行了理论分析和实验验证,结果表明:在0~1.2 N测量范围内,力实验灵敏度为889 pm/N,理论和实验的平均相对误差为6.6%,力分辨力为1.1 mN,位移灵敏度随着悬臂梁长度L的增大而减小,位移灵敏度在L为149 mm时为60.7 pm/mm,在L为99 mm时为200.3 pm/mm,位移分辨力为5μm,传感单元的线性度均达0.999以上,保持了优良的线性,可满足不同量程的微力和微位移应用场合。

In this paper,a dual physical quantity sensing unit of micro-force and micro-displacement based on fiber Bragg grating(FBG)is designed.A rectangular cantilever beam type elastic body structure and two FBG patch methods are adopted,which can improve the force and displacement sensitivity and realize temperature compensation.The displacement sensitivity can be adjusted by changing the fixed position and length of the cantilever beam.The performance of the sensing unit is theoretically analyzed and experimentally verified.The results show that the force test sensitivity is 889 pm/N in the 0~1.2 N measurement range,the theoretical and experimental average relative error is 6.6%,and the force resolution is 1.1 mN.The displacement sensitivity decreases with the increase of the cantilever beam length L.The displacement sensitivity is 60.7 pm/mm and 200.3 pm/mm respectively,when L is 149 mm and 99 mm.The displacement resolution is 5μm and the linearity of the sensing unit is above 0.999,which maintains an excellent linearity and can meet the application of micro-force and micro-displacement of different ranges.