基于角度偏差自校正的光纤形状传感结构设计

Design of Fiber Shape Sensing Structure and Angle Deviation Self-correction Algorithm

摘要:

光纤形状传感中FBG的放置角度误差会影响曲率的计算精度,从而增大形状反演的误差。为了实现传感胶棒的角度自校正,设计了一种自校正形状传感结构,在传感胶棒的感知截面上布设9个FBG,以120°等角度间隔作为基准位置,分别提取±10°位置上的应变,从而实现FBG响应与角度偏差的函数映射。提出了一种基于角度偏差自校正算法,通过适应度函数完成对传感参量α与k的阈值优化,实现任意角度偏差的自校正。仿真分析不同α与k条件下的响应关系,发现α具有很好的线性变化特性,k仅随主敏感FBG波动的特性。在单截面实验中,加载0~100N应力变化后,9个FBG的平均响应度介于[-1.012με/N,0.987με/N]之间。响应度的正负可以表征弯曲方向,相邻FBG的响应也具有很好的线性度。在组合截面实验中,根据反演结果重建传感胶棒三维结构,输出各点位坐标和应力值信息。

Abstract:

The error in placement angle of the fiber Bragg grating (FBG) in fiber optic shape sensing can affect the accuracy of curvature calculation, thereby increasing the error of shape inversion. To achieve self-correction of the angle of the sensing rubber rod, a self-correction shape sensing structure was designed. Nine FBGs were deployed on the sensing cross-section of the sensing rubber rod, with equal angle intervals of 120° as the reference positions, and strains were extracted at ±10° positions, thereby completing the functional mapping of the FBG response and angle deviation. A self-correction algorithm based on angle deviation is proposed, which optimizes the threshold of sensing parameters α and k through the fitness function to achieve self-correction of any angle deviation. A simulation analysis of the response relationship under different α and k conditions revealed that α had good linear variation characteristics, and k only fluctuated with the main sensitive FBG. In the single section experiment, the average response of the nine FBGs was between [-1.012με/N,0.987με/N] after loading 0~100N stress changes. The positive or negative response characterized the bending direction, and the responses of adjacent FBGs had good linearity. In the composite cross-section experiment, the three-dimensional structure of the sensing rubber rod was reconstructed based on the inversion results, and the coordinates and stress values of each point were output.