面向结构健康监测的无源RFID标签天线智能感知关键技术研究

Enabling intelligent sensing ability in addition to passive radio frequency identification (RFID) tags with identity and tracking capabilities is a new direction for low-cost sensor nodes. The cost, wireless channel, and receiver noise limits the sensitivity and reliability of the narrowband analog ultra-high frequency (UHF) RFID tag antenna based intelligent sensing technology. These limitations are the practical issues that put a brake on the application of this technology. Dedicated to crack detection in structural health monitoring (SHM), this project begins with system design. Through eigenmode analysis and electromagnetic sensing theory, this project uncovers the sensing mechanism, studies the dependencies of antenna impedance and detection reliability with the variation of crack profile and position, and design novel antenna sensors as well. Through automatic impedance matching and wireless impedance measurement, this project intends to compensate the decrease of the sensitivity resulting from the large-scale fluctuation. Through principal component analysis, this project tries to establish the physical relationship between feature extraction and eigenmode of the antenna and therefore to alleviate the influence of accuracy suffering from small-scale fluctuation and noise. This project aims to break through the limitations from communication to sensing for the narrowband analog RFID tag antenna based intelligent sensing. The implementation of this project develops UHF RFID based intelligent monitoring system for autonomous monitoring, positioning, and quantification of cracks, offers an important means for early warning of large-scale infrastructures in their life cycle, and provides a reliable big data source for monitoring in the era of internet of things (IoT).

赋予具有标识、追踪功能的无源RFID标签以智能感知能力，是低成本传感节点发展的新方向。受成本、无线信道及接收机噪声等限制，窄带模拟超高频RFID标签天线智能感知技术的灵敏度、精度及可靠性是阻碍其应用的关键问题。针对结构健康监测裂纹检测需求，本课题从系统设计出发，通过天线特征模式分析与电磁传感理论，揭示传感机理及天线输入阻抗和可靠性随裂纹形态、位置等变化并设计新型标签天线传感器；通过自动阻抗匹配及无线测量方法，对抗大尺度衰落引起的灵敏度降低问题；通过主成分分析，建立特征提取与天线模式之间的物理联系，抑制小尺度衰落及噪声对精度的影响。旨在突破窄带模拟标签天线智能感知技术通信对传感的限制。本课题的实施将建立基于超高频RFID的裂纹智能监测与评估系统，自主监测、定位并量化裂纹，为大规模设施生命周期内的早期预警提供重要手段，也为物联网时代的监测提供可靠的大数据来源。

天线传感器是天线领域的新技术，它不仅具备天线对波的收发功能，还具备天线场对周围环境的感知功能。基于RFID天线设计的新型电磁传感器，具有“无线”“无源”和“低成本”的优势，在结构健康监测领域具有潜在的应用价值。窄带与模拟影响超高频RFID天线传感器的灵敏度和可靠性，是限制RFID传感技术应用的关键科学问题。面向金属结构表面裂纹的健康监测需求，本课题建立了天线传感器的基本原理，指出了天线传感器的关键指标并提出了天线传感器的设计方法。.针对裂纹检测机理及鲁棒检测需求，本课题提出了基于形状微扰的裂纹量化方法，并发现裂纹检测灵敏度及位置影响与场的集中与均匀程度直接相关。进一步地，通过低剖面贴片天线传感器裂纹检测的量化研究，发现传感与通信能量相互竞争是限制两者性能同时提高的关键，并成功研制超高频RFID标签天线样机一套。提出了基于介质谐振器的极化可重构裂纹传感器，能实现裂纹方向和裂纹程度的同时检测，并成功研制介质谐振器样机两套。进一步地，提出了介质加载行波结构用于裂纹检测的方法，介质加载是为了场集中，而行波结构是为了使场均匀，从而可实现与位置无关的裂纹检测。.针对传感通信一体化需求，分别从天线设计、阻抗测量、特征提取三个方面提出相应方法：即提出了基于类电磁诱导透明的新型天线传感器，明模用于通信暗模用于传感，暗模采用环偶极子实现局域场增强，同时提高了检测灵敏度与通信距离，并成功研制窄带超高频频段RFID标签天线样机一套；提出了软硬件协同的天线阻抗远程调谐方法，通过标签天线阻抗在标签端的数字化调谐，消除模拟信道传输对传感性能的影响，可提高检测的可靠性；提出了时频融合的特征提取方法，可抑制提离对检测的影响。.本课题还成功开发了基于商用阅读器的RFID测试系统一套，可读取RFID标签芯片EEPROM并扫描阅读器的发送功率等。.本课题建立了天线传感器的基本理论并提出传感通信一体化设计方法，对于天线领域的发展具有重要的科学意义，研究的各类天线传感器对新型结构健康监测网络的构建具有重要的工程价值，在航天国防核能等众多领域具有广泛的应用前景。