Design of Fiber Shape Sensing Structure and Angle Deviation Self-correction Algorithm
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[-1.012 με/N,0.987 με/N]after loading 0～100 N 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.
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