螺旋型光纤传感软体操作臂状态测量及特性分析

微创手术软体操作臂是微创外科和机器人领域的科学前沿和研究热点，对提升微创手术水平至关重要。现有视觉、电子和光电等传感方法尚未解决软体操作臂的状态测量问题，以直线型布设在软体操作臂中的光纤传感器，在柔性操作臂伸展和弯曲等运动时存在易断裂和可重复性差等问题，未能实现手术操作臂的闭环控制，限制了其手术应用。为此，提出了一种基于螺旋型光纤传感的软体操作臂状态测量方法，并对其传感特性进行了研究。不同于直线布设光纤的传感方法，螺旋型布设光纤的传感方法可以实现可伸缩软体操作臂的测量，防止光纤在软体操作臂中的错位，满足可伸缩弯曲软体操作臂的测量需求。通过理论分析气动驱动软体操作臂伸缩和弯曲的运动特性，利用光纤上刻写的布拉格光栅传感点，建立软体操作臂中螺旋型光纤光栅的传感模型，推导出光纤光栅中心波长漂移量和软体操作臂弯曲曲率之间的关系。最后，为了验证螺旋型光纤光栅在软体操作臂中的传感性能，对其传感灵敏度和稳定性等进行了实验测试。实验结果表明:提出的螺旋型光纤传感方法可实现操作臂伸长10%、弯曲角度达到180°时的状态测量，且操作臂理论弯曲角度和光纤传感的误差最大为9%，传感灵敏度可达12.55 pm/(°)，满足软体操作臂伸缩和各向弯曲操作时的测量需求。

State measurement and sensing characteristics analysis of soft maniputator based on helical optical fiber

The soft surgical manipulator is the scientific frontier and research hotspot in the field of minimally invasive surgery and robotics, which is very important to improve the level of minimally invasive surgery. The existing sensing methods, such as vision, electronics and photoelectricity, have not solved the problem of measuring the state of the arm of soft gymnastics. The optical fiber sensor arranged in a straight line in the soft manipulator is easily broken and repeatable when the flexible manipulator is stretched and bent. Problems such as poor sex, failed to achieve closed-loop control of the surgical manipulator, limiting its surgical application.Therefore, a state measurement method of soft manipulator based on helical optical fiber sensor was proposed, and its sensing characteristics were studied. Different from the linear optical fiber sensor method, the unique helical structure could prevent the sensor from dislocation and support the ductility of the material, which was convenient to meet the measurement requirements of the operating arm when it moved. Based on the theoretical analysis of the movement characteristics of the expansion and bending of the pneumatic soft maniputator, the sensing model of the helical fiber grating in the soft maniputator was established by using the FBG sensing points engraved on the optical fiber, and the relationship between the center wavelength drift of the FBG and the bending curvature of the soft maniputator was deduced. Finally, in order to verify the sensing performance of the helical fiber grating in the soft manipulator, the sensitivity and stability of the sensing were tested. The experimental results show that the helical optical fiber sensing method proposed can realize the state measurement when the manipulator is extended by 10% and the bending angle reaches 180°. The error between the theoretical bending angle of the manipulator and the optical fiber sensing is up to 9%, and the sensing sensitivity is up to 12.55 pm/(°) which can meet the needs of the measurement when the soft maniputator is retracted and bent in all directions.