NSF: CCSS: Precision Positioning for Structural Monitoring by Embedded RFID Tags

NSF：CCSS：嵌入式 RFID 标签进行结构监控的精确定位

• 批准号: 1945918
• 负责人: Edwin Kan
• 金额: $ 36.87万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-02-15 至 2023-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1945918&HistoricalAwards=false
• 关键词: NSF; CCSS; Precision; Positioning; Structural

Accurate noninvasive monitoring of structural integrity is critical for civil engineering research and has a high national interest on healthy infrastructure and public welfare. Disasters such as the collapses of bridges and dams have very high social cost for the society not only for the disaster repair and relief, but also in terms of preventive maintenance budget and public panic factors. Previous nondestructive low-strain pile integrity testing methods such as nuclear radiation, ultrasound, sonic, radar, optical fibers and accelerometers can retrieve marker displacement and material changes, but all have applicability limitations in each of their long history of development. To date, structural integrity assurance would take great benefits from a convenient, non-invasive, reliable and cost-effective method that can be broadly deployed for long-term monitoring throughout the lifetime of the structure. In this project, a new marker-based ultra-high precision positioning system is envisioned, which employs the passive radio-frequency identification (RFID) tags to directly measure internal displacement of specific structural points caused by creep and deformation. These tags can be embedded in new piles and building materials to provide a novel alternative to structural integrity testing, replacing or complementing existing methods. As the passive tag never needs maintenance or recharging, it can have a lifetime as long as the structure. Integrity testing can be simply executed by placing the custom RFID reader at designated external points to report the precise location or vibration of the buried tags. The sensing radio frequency is selected properly so that it is not too high that would result in poor material penetration or too low that would result in poor ranging precision. This proposed structural "radar" enables the seeing of the previously unseen structural concerns and stimulates students' interest of engineering wonders that will have positive impacts to society. This project aims to establish a new precision radio frequency (RF) ranging and locating method for noninvasive long-term structural integrity monitoring. The ultra-high frequency signal can penetrate deep into the building materials to locate specific marker tags buried in the structure with spatial accuracy around 20 microns and temporal resolutions below millisecond. The method is based on the passive harmonic RFID platform and backscattered 2nd harmonic of the impinging signal to minimize the phase noise from self-jamming. The remaining phase noises were further mitigated by frequency strategy, stable reference, moving average, and zero-point calibration. The research tasks include RF frontend improvement, system-level improvement, and civil structure demonstration, which will bring forth verified demonstration of the new noninvasive sensing scheme in realistic scenarios with the targeted performance and reliability. Multiple incoherent frequencies will be employed in RF frontend to simultaneously improve both operational distance and the spatial resolution. Multi-path variation tolerance can be further mitigated by randomizing antennas and artificial beamforming. Geometrical dilution of precision in 3D locating will be mitigated by antenna placement and evaluation of angle of arrival, so that the system can achieve 3D locating with 5-micron accuracy and 1 million samples per second. The system will be experimentally demonstrated in realistic civil structures of concrete mixes and weight-bearing beams. By using multi-tag method with known tag separation, permittivity change due to temperature and metal corrosion sensing will be investigated. If successful, the resulting high-precision strain sensor can bring forth a cost-effective noninvasive method that will greatly improve the structural integrity monitoring. The precision locating method can also be applied to many other applications in precision instrument, foundation engineering, and human-machine interface.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

准确的无创结构完整性监测对土木工程研究至关重要，对健康的基础设施和公共福利具有很高的国家利益。桥坝垮塌等灾害无论是在抢险救灾方面，还是在预防性维护预算和公众恐慌因素方面，都给社会带来了非常高的社会成本。以往的无损低应变桩完整性检测方法，如核辐射、超声、声波、雷达、光纤、加速度计等，都可以检索到标记位移和材料变化，但在其长期的发展历史中，都存在适用性的局限性。迄今为止，结构完整性保证将从一种方便、无创、可靠和经济有效的方法中获益，这种方法可以在结构的整个生命周期内广泛应用于长期监测。本课题设想了一种新的基于标记的超高精度定位系统，该系统采用无源射频识别（RFID）标签直接测量特定结构点因蠕变和变形引起的内部位移。这些标签可以嵌入到新的桩和建筑材料中，为结构完整性测试提供一种新的替代方案，取代或补充现有的方法。由于无源标签不需要维护和充电，因此它的寿命与结构一样长。完整性测试可以通过将定制的RFID读取器放置在指定的外部点来简单地执行，以报告埋藏标签的精确位置或振动。传感射频选择适当，使其不会太高而导致材料穿透性差，也不会太低而导致测距精度差。这种提议的结构“雷达”能够看到以前看不到的结构问题，并激发学生对工程奇迹的兴趣，这将对社会产生积极影响。本课题旨在建立一种新的精密射频测距和定位方法，用于无创长期结构完整性监测。超高频信号可以穿透建筑材料深处，定位埋在结构中的特定标记标签，空间精度约为20微米，时间分辨率低于毫秒。该方法基于无源谐波RFID平台，利用冲击信号的反向散射二次谐波，最大限度地减少自干扰产生的相位噪声。通过频率策略、稳定参考、移动平均和零点校准等方法进一步减小了剩余相位噪声。研究任务包括射频前端改进、系统级改进和民用结构演示，为新型无创传感方案提供具有目标性能和可靠性的现实场景验证。射频前端将采用多个非相干频率，以同时提高操作距离和空间分辨率。随机化天线和人工波束形成可以进一步降低多径变异容差。通过天线的放置和到达角的评估来缓解三维定位精度的几何稀释，使系统能够实现5微米精度和每秒100万个样本的三维定位。该系统将在混凝土配合料和承重梁的实际土木结构中进行实验验证。利用已知标签分离的多标签方法，研究温度和金属腐蚀传感引起的介电常数变化。如果成功，所得到的高精度应变传感器可以带来一种经济有效的无创方法，将大大提高结构完整性监测。该方法还可应用于精密仪器、基础工程、人机界面等领域。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。