Direct Fibre Optic Shape Sensing for Large Scale Engineering Structures

形状传达了有关易于可视化和解释的结构的信息，其动态、绝对测量在以下应用中具有重要意义：医学(跟踪手术过程中微创仪器的移动)、风力涡轮机(监测涡轮叶片形状，以实现主动载荷缓解控制)、航空航天(监测变形机翼、液压软管和电缆织机)、土木工程(监测陆上和近海结构的健康状况)、铁路(监测轨道和车辆)以及体育和游戏行业(运动学运动测量)。直接光纤形状传感(DFOSS)是一项具有颠覆性的技术，有可能产生革命性的影响。DFOSS允许光纤路径以及光纤连接到的结构在三维空间中进行跟踪。DFOSS的一个关键优点是，形状直接在传感光纤中确定，从而消除了对结构应变传递的依赖，从而消除了对结构模型的要求。例如使用胶带对传感纤维进行简单的表面安装就足够了。这里提出的DFOSS方法基于克兰菲尔德大学首创的光纤段干涉测量方法，该方法采用了一种简单、经济高效且坚固耐用的询问系统，该系统利用久经考验的电信激光二极管、探测器和光纤组件来提供高灵敏度的高速动态曲率测量。我们初步实现的方法适用于相对测量小结构的形状(长度可达5m)，传感量规长度在1 cm到1m的范围内，并已在空客H135直升机上以~400rpm旋转的5m直升机上进行了成功的地面试验。这项提议旨在解决扩展DFOSS方法在更大尺度物体、风力涡轮机叶片和飞机机翼上进行形状绝对测量所涉及的科学挑战(测量长度高达100米，空间分辨率高达1M量级，数据速率高达1千赫)。物体的尺寸和预期的形状变化率带来的挑战将需要重大创新，推动测量配置的根本演变，同时保持该方法的低成本和健壮性质。还需要在处理作为该方法核心的长段多芯光纤方面进行创新，并在按照已知的路线进行部署的手段方面进行创新。该方法的设计和开发将受到风能和航空航天领域实际测量挑战的启发，目的是展示其在波音737机翼上的使用，例如测量机翼顶升的响应，以及在风力涡轮机上，测量叶片形状变化和叶尖位移，对叶片进行振动特征分析，以及对故障叶片进行损坏位置识别。

Shape conveys information about a structure that is easily visualized and interpreted, and its dynamic, absolute measurement has significance in applications that span medicine (tracking the movement of minimally invasive instruments during surgery), wind turbines (monitoring turbine blade shape for active load alleviation control), aerospace (monitoring morphing wings, hydraulic hoses and electric cable looms), civil engineering (health monitoring of onshore and offshore structures), rail (monitoring tracks and rolling stock) and the sports and gaming industries (kinematic motion measurements). Direct fibre optic shape sensing (DFOSS) is a disruptive technology that has the potential to have a transformative impact. DFOSS allows the fibre path, as well as the structure to which the fibre is attached, to be followed through space in three dimensions. A key advantage of DFOSS is that the shape is determined directly within the sensing fibre, removing the dependence on strain transfer from the structure and thus the requirement for a model of the structure. Simple surface mounting of the sensing fibre, for example using adhesive tape, is sufficient. The DFOSS approach proposed here is based on Fibre Segment Interferometry, an approach pioneered by Cranfield University, which employs a simple, cost-effective and robust interrogation system exploiting well-proven telecoms laser diodes, detectors and optical fibre components to offer highly sensitive high-speed dynamic curvature measurements. Our initial implementation of the approach is suitable for relative measurement of the shape of small structures (of length upto 5 m), with a sensing gauge length in the range 1cm to 1m and has been successfully trialled on a 5m helicopter rotor rotating at ~400rpm in a ground test on an Airbus H135 helicopter. This proposal aims to solve the scientific challenges involved in extending the capabilities of this DFOSS approach to undertake absolute measurements of shape on larger scale objects, wind turbine blades and aircraft wings (measurement lengths up to 100m, with spatial resolution of the order 1m and data rates of up to 1 kHz). The challenges introduced by the scale of the objects and the anticipated rates of change of shape will require significant innovation, driving a radical evolution of the measurement configuration while maintaining the low cost and robust nature of the approach. Innovation is also required in the processing of the long lengths of multicore optical fibre at the heart of the approach and in the means for its deployment with a known alignment. The design and development of the approach will be informed by real measurement challenges in wind energy and aerospace, with the aim to demonstrate its use on the wing of Boeing 737, for example measuring the response to the jacking of the wing, and on a wind turbine, measuring blade shape changes and blade tip displacement, undertaking vibration characterisation of the blade, and damage location identification on a faulty blade.