Direct Fibre Optic Shape Sensing for Large Scale Engineering Structures

形状传达了关于易于可视化和解释的结构的信息，其动态绝对测量在医学应用中具有重要意义（跟踪手术过程中微创器械的运动）、风力涡轮机（监测涡轮机叶片形状，用于主动载荷减缓控制），航空航天（监控变形机翼、液压软管和电缆织机），土木工程（陆上和海上结构的健康监测）、铁路（监测轨道和机车车辆）以及体育和博彩业（运动学运动测量）。直接光纤形状传感（DFOSS）是一项具有变革性影响的颠覆性技术。DFOSS允许在三维空间中跟踪光纤路径以及光纤所连接的结构。DFOSS的一个主要优点是，形状直接在传感光纤内确定，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。传感光纤的简单表面安装（例如使用胶带）就足够了。这里提出的DFOSS方法是基于光纤段干涉测量法，这是由克兰菲尔德大学首创的方法，它采用了一种简单、具有成本效益和强大的询问系统，利用成熟的电信激光二极管、探测器和光纤组件提供高灵敏度的高速动态曲率测量。我们的初步实施的方法是适合于相对测量的形状的小结构（长度达5米），与传感标距长度在1厘米至1米的范围内，并已成功地试用在空中客车H135直升机上的地面测试中旋转在~ 400转/分的5米直升机旋翼。该提案旨在解决在扩展这种DFOSS方法的能力方面所涉及的科学挑战，以便对较大尺度物体、风力涡轮机叶片和飞机机翼进行绝对形状测量（测量长度可达100米，空间分辨率为1米量级，数据速率高达1 kHz）。物体的规模和预期的形状变化率带来的挑战将需要重大的创新，推动测量配置的根本发展，同时保持该方法的低成本和鲁棒性。在处理处于该方法核心的长多芯光纤以及以已知的对准方式部署光纤的手段方面也需要创新。风能和航空航天领域的真实的测量挑战将为该方法的设计和开发提供信息，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的使用，测量叶片形状变化和叶尖位移，进行叶片的振动表征，以及故障叶片的损伤位置识别。

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.