Research On The Detection And Transmission Method Of Characteristic Parameters Of Chipless RFID Strain Sensors

Timely and effective strain monitoring of modern large civil infrastructures is essential to ensure their long-term safe operation.RFID is an emerging wireless sensing technology based on the Internet of Things(IoT).The application of RFID strain sensors in the field of largescale structural health monitoring(SHM)can solve the shortcomings of traditional strain sensors that rely on active wiring and data lines,and effectively expand the coverage of the sensing system.At present,the research of RFID strain sensors usually focuses on the identification of mechanical properties and lacks the fusion design of coding functions,while chip RFID sensors are limited by the computing power of integrated chips and high production costs,so the development of low-cost chipless RFID strain sensors is one of the future development directions of large-scale IoT sensing systems.Although chipless RFID sensors have the advantages of non-contact measurement,lowcost production,and allowing multi-parameter sensing,existing chipless RFID sensing and identification systems are often limited using large and expensive devices and lack flexibility,and the extraction of characteristic parameter signals from chipless sensing devices has problems such as short detection and transmission distances and low identification efficiency.This paper is dedicated to propose a more flexible and economical automatic identification and data transmission scheme based on chipless RFID strain tag information.The full research paper and its innovations are as follows:(1)In response to the development and challenges of nondestructive testing methods in new structural health monitoring systems,this paper introduces a new passive RFID integrated antenna sensor for wireless sensing and metal strain monitoring,and describes the working principle of strain sensor metal strain detection and the process of multi-parameter integration,and realizes the wired and wireless measurement of scattered signals from chipless RFID strain tags,and provides a comprehensive analysis of RFID strain sensors from multiple perspectives,including strain sensing mechanism,feature parameter extraction,and RFID data transmission and processing.(2)The feasibility of RFID patch antenna as a strain sensor design is theoretically deduced,and the electromagnetic modeling and dimensional optimization of RFID patch antenna are performed by simulation software HFSS.After that,a strain scenario simulation is established to simulate the change of electromagnetic characteristics of the antenna sensor under large strain,which provides a theoretical basis for the experimental strain measurement.Finally,the consistency with the simulation analysis is verified by wired strain tension experiments,and the experimental results are consistent with the theoretical derivation.(3)A multi-stem U-shaped resonator based on microstrip line coupling is designed for strain sensor tag coding.The high Q band resistance filtering characteristics of the U-shaped resonator are analyzed by building a resonator equivalent circuit.The feasibility of using the resonator in a dual-port network with multiple resonant cascade tag design is verified by combining HFSS simulation design,ADS equivalent circuit and physical measurements,and achieving more resonant coding positions in a compact antenna size and the same operating band.(4)An ultra-wideband transceiver antenna and reader antenna that can be used for wireless measurement were designed,and the experimental results of wired and retransmission-based wireless measurements were compared by experimentally testing several sets of strain tags of aluminum plate specimens,and the longitudinal strain sensitivity of the tags under the wired experiment was-1.72 k Hz/με,and the longitudinal sensitivity of the tags under the wireless strain measurement was-1.44 k Hz/με.A low-cost chipless RFID tag smart detection scheme that can extract the characteristic parameters of the tag is introduced.By building a lightweight VNA-based metal strain wireless spectrum acquisition and data transmission platform,the measured tag longitudinal strain sensitivity is-1.48 k Hz/με,and the wireless transmission error is less than 3% compared with the wireless strain measurement result of-1.44 k Hz/με,which verifies the feasibility of lightweight VNA-based laboratory strain detection and automated data acquisition.