Chipless RFID sensor systems for structural health monitoring

Ph. D. ThesisDefects in metallic structures such as crack and corrosion are major sources of catastrophic failures, and thus monitoring them is a crucial issue. As periodic inspection using the nondestructive testing and evaluation (NDT&E) techniques is slow, costly, limited in range, and cumbersome, novel methods for in-situ structural health monitoring (SHM) are required. Chipless radio frequency identification (RFID) is an emerging and attractive technology to implement the internet of things (IoT) based SHM. Chipless RFID sensors are not only wireless, passive, and low-cost as the chipped RFID counterpart, but also printable, durable, and allow for multi-parameter sensing. This thesis proposes the design and development of chipless RFID sensor systems for SHM, particularly for defect detection and characterization in metallic structures. Through simulation studies and experimental validations, novel metal-mountable chipless RFID sensors are demonstrated with different reader configurations and methods for feature extraction, selection, and fusion. The first contribution of this thesis is the design of a chipless RFID sensor for crack detection and characterization based on the circular microstrip patch antenna (CMPA). The sensor provides a 4-bit ID and a capability of indicating crack width and orientation simultaneously using the resonance frequency shift. The second contribution is a chipless RFID sensor designed based on the frequency selective surface (FSS) and feature fusion for corrosion characterization. The FSS-based sensor generates multiple resonance frequency features that can reveal corrosion progression, while feature fusion is applied to enhance the sensitivity and reliability of the sensor. The third contribution deals with robust detection and characterization of crack and corrosion in a realistic environment using a portable reader. A multi-resonance chipless RFID sensor is proposed along with the implementation of a portable reader using an ultra-wideband (UWB) radar module. Feature extraction and selection using principal component analysis (PCA) is employed for multi-parameter evaluation. Overall, chipless RFID sensors are small, low-profile, and can be used to quantify and characterize surface crack and corrosion undercoating. Furthermore, the multi-resonance characteristics of chipless RFID sensors are useful for integrating ID encoding and sensing functionalities, enhancing the sensor performance, as well as for performing multi-parameter analysis of defects. The demonstrated system using a portable reader shows the capability of defects characterization from a 15-cm distance. Hence, chipless RFID sensor systems have great potential to be an alternative sensing method for in-situ SHM.Indonesia Endowment Fund for Education (LPDP

IMPLEMENTASI PENGIRIM OFDM PADAFPGAXILINX SPARTAN-3E

OFDM adalah sebuah teknik modulasi dengan banyak pembawa yang mampu menyediakan layanan transmisi paralel dengan pesat bit tinggi. OFDM sangat efisien dalam penggunaan lebar pita karena menggunakan sub pembawa yang ortogonal sehingga spektrum antar sub pembawa dapat saling tumpang tindih satu dengan yang lain. Banyaknya penerapan OFDM pada standar-standar komunikasi menyebabkan munculnya berbagai penelitian mengenai implementasi OFDM pada FPGA. Obyek dari penelitian ini adalah mengimplementasikan sebuah model pengirim OFDM pada sebuah chip FPGA Xilinx Spartan-3E. Desain dibagi dalam beberapa bagian yang meliputi pengubah serial ke paralel, pemeta 16-QAM, IFFT 8 titik, dan pengubah paralel ke serial. 16-QAM merupakan salah satu skema modulasi yang digunakan pada standar komunikasi IEEE 802.11a. Desain dibuat dengan VHDLpada perangkat lunak Xilinx ISE 9.2i. Keluaran dari pengirim OFDM ditampilkan pada antarmuka LCD pada papan pengembangan Xilinx Spartan-3E dan dibandingkan dengan keluaran pengirim OFDM serupa yang dimodelkan pada Matlab. Sebagai hasilnya, implementasi pengirim OFDM mampu menunjukkan kinerja yang benar dan sangat mendekati hasil Matlab. Dari segi kapasitas, FPGA Xilinx Spartan-3E sangat mencukupi untuk kebutuhan rancangan dan berpotensi untuk pengembangan implementasi sistem yang lebih besar

Non-invasive Frozen Meat Monitoring System Using UHF RFID Tag Antenna-Based Sensing and RSSI

The conditions of frozen meat products must be closely monitored in cold chain logistics (CCL) to maintain their quality and safety. Sensing and monitoring meat products are currently invasive, costly, and lacking tracing capabilities. Therefore, developing a wireless, passive, and cost-effective sensing system capable of tracking and monitoring remains challenging. This work investigates the UHF RFID system performing antenna-based sensing for monitoring frozen meat using the received signal strength indicator (RSSI) data. A commercial off-the-shelf (COTS) UHF RFID reader is programmed through a single-board computer to acquire the RSSI data throughout the RFID 902-926 MHz band. In the experiments, RSSI data from an RFID inlay tag affixed to a defrosted frozen meat sample is acquired for approximately 20 minutes. Then, the RSSI data is recorded periodically during the changes in the sample condition. The experimental results signify that the RSSI data have monotonic relationships with the temperature and hardness of the meat sample. The three-degree polynomial regression models are constructed to show the non-linear relationships between the RSSI and the frozen meat condition. During defrosting, the RSSI lowers as the meat temperature rises and the hardness reduces. Therefore, antenna-based sensing employing the RFID RSSI data can detect changes in frozen meat temperature and hardness, allowing conditional fluctuations in the CCL to be monitored. This work paves the way for low-cost IoT-based sensing systems for improving food safety in cold chain applications

UHF RFID Tag Antenna-based Sensing for Non-destructive Monitoring of Frozen Meat Using the RSSI

In cold chain logistics (CCL), the condition of frozen meat products must be tightly controlled to ensure their quality and safety to the consumers. The current methods of sensing and monitoring meat products are destructive, expensive, and without tracing capabilities. Therefore, a wireless, passive, and cost-effective sensing method is desired to perform both tracing and monitoring. This work investigates the use of UHF RFID system performing antenna-based sensing for monitoring frozen meat using the received signal strength indicator (RSSI). A commercial off-the-shelf (COTS) UHF RFID reader is programmed to acquire the RSSI data throughout 902-926 MHz band. RSSI data from an RFID inlay tag antenna attached to a frozen meat sample is collected for 20 to 30 minutes. By experimenting, we have found relationships between the acquired RSSI data and the temperature and hardness conditions of the defrosting frozen meat. The results signify that the RSSI data have monotonic but nonlinear relationships with the temperature and hardness of the meat sample. During the meat defrosting process, the RSSI decreases with the increasing temperature and the decreasing hardness. Therefore, antenna-based sensing using RFID RSSI data can indicate the variation of frozen meat temperature and hardness, which helps monitor conditional variations in the CCL. © 2022 IEEE