为了研究光纤布拉格光栅(Fiber Bragg Grating, FBG)在感知形状变形时, 低杨氏模量的柔性材料与高杨氏模量的刚性二氧化硅的结合是否存在刚-柔应变耦合引起的蠕变、应变传递差异等实际问题。采用软体机器人常用的硅胶和聚二甲基硅氧烷(polydimethylsiloxane, PDMS)材料, 制备了4个不同杨氏模量的软体基体, 在每个软体基体内植入了3个FBG, 形成4个具备形状测量能力的柔性传感器, 并进行弯曲测试, 然后建立应变传递模型验证了实验结果与理论推导的一致性。结果表明: 软体基体和FBG结合时存在刚-柔耦合引起的蠕滑问题, 约30 min后趋于耦合稳定。其次, 4个柔性传感器内的3支FBG耦合稳定后的波长漂移量均表现出较好的线性和一致性。此外, FBG与基体的刚-柔性差异越大, 耦合蠕滑越严重, 应变传递引起的波长漂移量越小。其中, 最大应变传递率为0.680, 最小应变传递率为0.260, 最大灵敏度为56.649, 最小灵敏度为35.668。研究结果为基于植入式光纤光栅的软体机器人形状测量技术的研究提供了科学参考。

To analyze whether the combination of flexible materials with low Young′s moduli and rigid silica with a high Young′s modulus produces any practical problems, such as creep or strain transfer differences caused by rigid-flexible strain coupling when the fiber Bragg grating(FBG) senses shape deformation, four different Young′s modulus soft matrices were prepared by using silica gel (commonly used in soft robots) and polydimethylsiloxane (PDMS). Three FBGs were implanted in each soft matrix to form four flexible sensors with shape measurement capabilities and subjected to bending tests. The consistency between the experimental results and the theoretical derivation was verified theoretically via the strain transfer model.The results show that there is a creep-slip problem caused by rigid-flexible coupling when the soft matrix and FBG are combined, with the wavelength drift tending to be couple stable after about 30 minutes. Following creep stabilization, the wavelength drift of the three FBGs in the four flexible sensors shows good linearity and consistency. In addition, the larger the rigid-flexible difference between the fiber and the substrate, the more severe the coupling creep and the smaller the strain transfer rate. The maximum and minimum strain transfer rate are 0.680 and 0.260, respectively, while the maximum and minimum sensitivities are 56.649 and 35.668, respectively. These results provide a scientific reference for research focusing on the shape measurement technology of soft robots using implanted FBGs.