利用光纤曲率传感器重建三维曲面结构

Three dimensional reconstruction of curved shape based on curvature fiber optic sensor

为了实现对弯曲结构的三维空间数据的测量与重建,建立了光纤曲率传感器的准分布式测量系统。对该系统中传感器的布置方式、空间弯曲曲率和扭转角的测量及三维结构重建方法进行了研究。首先,将光纤曲率传感器绕成环形,布置在柔性基底的两个对称表面,组成准分布式测量系统。根据线性叠加原理,同时测量出结构的弯曲和扭转变形。使用光纤曲率传感器提供的弯曲和扭转信息,采用微分几何的方法,建立由曲线切线和曲率确定的运动坐标系,在运动坐标系中根据空间结构的扭转角确定密切平面。然后,在密切平面中进行曲线的弯曲计算和运动坐标系的变换分析,并进行拟合过程的公式推导。最后,对该方法进行了试算验证,并利用准分布式测量系统对两支点间距为500 mm的简支梁进行了结构重建。结果显示,在相邻两检测点进行20点插值时,简支梁曲线的最大偏差为1.1 mm,表明设计的系统和重建方法能够较高精度地实现曲面结构的三维重建。

In order to realize the 3D measurement and reconstruction for a curved shape,a quasi-distributed measuring system based on curvature fiber optic sensors is presented and its algorithms such as the layout of sensors,measurements of curvature and torsion angles,and 3D reconstruction methods are investigated.Firstly,a number of looped fiber optic sensors are arranged on the two symmetrical surfaces of a flexible tape,and a quasi-distributed measuring system is established to measure bend and torsion deformations simultaneously using linear superposition theorem.Based on the bend and torsion data provided by curvature fiber optic sensors,a moving coordinate system is established by the curve tangent and curvature using a differential geometry method,and the osculating plane is determined by a torsion angle in the moving coordinate system.Then,the curve bending is calculated and the recursion of coordinate system is analyzed in the osculating plane.The correlative formulas are deduced and the method is validated by examples.Finally,the quasi-distributed measuring system is used to reconstruct the curve of a simply supported beam with a length of 500 mm.Results show that when 20 points are inserted between two measured points,the maximum deviation of reconstructed curve is 1.1 mm,which means the measurement system and the reconstruction method can reconstruct 3D shapes precisely.