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关键词： RFID antenna sensor   Nanocomposites   Low cost   Multidimensional sensor  

摘要： RFID technology has matured significantly and plays a crucial role in industrial automation. In breweries, precise monitoring and control of environmental data are required at various stages of the brewing process, including humidity, light exposure, and alcohol concentration during fermentation. To facilitate the monitoring of multiple environmental parameters in complex production environments, a passive RFID multidimensional sensor is designed to cater to brewery automation. The sensor is composed of a tri-frequency ELC resonator antenna designed by HFSS simulation. The passive RFID multidimensional sensor operates stably under ambient conditions for light intensity from 9.7 to 39.1 klx, humidity from 20 % to 80 % RH, and ethanol concentration from 0 to 1,800 ppm. In an environment with light intensity between 9.7 and 39.1 klx, the amplitude change is 20 dB, sensitivity is 0.67 dB/klx, and response time is 15.1 +/- 0.7 s. In the RH range of 20-80 %, the measured frequency shift is 0.16 GHz, sensitivity is 2 MHz/%RH, and response time is 6.4 +/- 0.5 s. For ethanol concentrations between 0 to 1800 ppm, the amplitude change is 17.9 dB, sensitivity is 0.01 dB/ppm, and response time is 25.1 +/- 1.2 s. This sensor is economical while boasting zero power consumption, fast response, excellent stability, and good accuracy. It has large potential in multi-parameter monitoring, especially breweries, by offering stable quality and enhancing the production efficiency.

关键词： Protocols   Vectors   Monitoring   Mobile computing   Iterative methods   Interference   Vegetation   RFID tags   Optimization   Modulation   RFID   key tags   missing tag identification   time efficiency  

摘要： Radio frequency identification (RFID) system has been extensively employed to track missing items by affixing them with RFID tags. Many practical applications require to efficiently identify missing events for a specific subset of system tags (called key tags) due to their elevated importance. Existing methods primarily aim to identify all tags, which makes it challenging to specifically identify key tags because of interference from other non-key tags (called ordinary tags). In light of this, several key tag identification methods follow a two-step scheme that filters ordinary tags first and then identifies key tags. Nevertheless, this wastes too much time on tag filtering, resulting in low time efficiency. This paper presents a novel missing key tag identification protocol with two creative designs to gain high efficiency. First, we develop a novel verification technique that can rapidly determine the presence or absence of key tags amid the scenarios with both key tags and ordinary ones. By combining the ON-OFF Keying modulation, we could verify multiple key tags in a single slot, thereby reducing the total slots required. Second, we design a new selection technique that efficiently selects the unverified key tags for further verification, while filtering out the verified key tags and irrelevant ordinary tags to avoid redundant data transmission. Additionally, we present an enhancement protocol that leverages a preselection technique to avoid collecting useless tag responses, further boosting efficiency. We carry out rigorous theoretical analysis to optimize the performance of the proposed protocols. Both simulations and practical experiments demonstrate that our method is markedly superior to state-of-the-art solutions.

关键词： Fabrication   Frequency synthesizers   Analytical models   Sensitivity   Resonant frequency   Chipless RFID   Laser modes   Etching   Resonance   Encoding   Chipless RFID tags   design methodology   high encoding capacity   resonator design  

摘要： This paper presents a class of novel fabrication-tolerant resonator design for high-capacity chipless RFID tags. The proposed resonator is based on a high-quality-factor grounded dipole with a single etched slot of variable length. By controlling the slot length, the resonant frequency can be adjusted while exhibiting much lower sensitivity to design variables compared to conventional dipole resonators. This makes the design resilient to fabrication tolerances, a critical requirement for mm-wave frequency bands. This feature enables a two-step fabrication process: first, producing high-precision master tags (e.g., via roll-to-roll fabrication), and second, customizing them by etching slots using a flexible method like laser etching. The presence of a ground plane provides isolation from the tagged object, enabling application to diverse materials and geometries. An analytical model is derived to establish the relationship between slot length changes and resonant frequency shifts, enabling efficient design optimization. Sensitivity analysis shows the proposed resonator has a single parameter sensitivity of 0.008 (feasibility), and overall sensitivity of 0.04 (stability) under +/- 50 mu m fabrication tolerance, over two orders of magnitude and half lower than the sensitivity of 1 for conventional dipoles. The resonator design is validated through simulations and experiments, demonstrating its potential for high-capacity, fabrication-tolerant chipless RFID tags.

关键词： Greenhouse   soil moisture   RFID   low-cost  

摘要： Intelligent irrigation based on measurements of soil moisture levels in every pot in a greenhouse can not only improve plant productivity and quality but also save water. However, existing soil moisture sensors are too expensive to deploy in every pot. We therefore introduce GreenTag, a low-cost RFID-based soil moisture sensing system whose accuracy is comparable to that of an expensive soil moisture sensor. Our key idea is to attach two RFID tags to a plant's container so that changes in soil moisture content are reflected in their Differential Minimum Response Threshold (DMRT) metric at the reader. We show that a low-pass filtered DMRT metric is robust to changes both in the RF environment (e.g., from human movement) and in pot locations. In addition, we propose a fast DMRT acquisition algorithm and a time-efficient tag query protocol, which can reduce the sensing latency by 90%. In a realistic setting, GreenTag achieves a 90-percentile moisture estimation errors of 5%, which is comparable to the 4% errors using expensive soil moisture sensors. Moreover, this accuracy is maintained despite changes in the RF environment and container locations. We also show the effectiveness of GreenTag in a real greenhouse.

关键词： Counting   Precision livestock farming   Swine  

摘要： Counting pigs accurately is an important part of maintaining animal inventories, reporting production metrics, and planning for pig movements and pork product flows. Manual counting is time consuming and error-prone, making automated technology counting methods attractive alternatives for swine producers. This study evaluated a commercial ultra-high frequency radio-frequency identification (UHF-RFID) system's performance in counting nursery pigs moving through a hallway. Preliminary testing was conducted in a controlled laboratory setting to ensure all tags were detectable by all readers, followed by evaluation of various reader settings and positions to determine the most reliable configurations. Through preliminary testing it was determined that a maximum read power of 25 was the most suitable for this experiment. Furthermore, three reader positions achieved similar tag detection accuracies and were selected for field testing: Low, Mid-Perp, and Mid-Angle. A total of 39 weaned pigs were given RFID ear tags and placed into four groups based on bodyweight. Three RFID readers were mounted on the same side of the nursery hallway, all at a read power of 25. An RGB camera was secured to the ceiling over each RFID reader to record pig movements and investigate tag non-detection events. Pigs were uniquely marked with livestock paint to enable individual animal identification in the videos. Each group was walked past the RFID readers a total of ten times, with five passes on the left and five passes on the right. This was repeated for all reader positions (Low, MidPerp, and MidAngle). Ultimately, it was found that reader location within the room had the greatest influence on tag detection accuracy. The middle reader at the Mid-Angle position had the highest percentage of detections (78.0 %, SE = 7.1 %). For this position, the right side movements (i.e., ear tag on the same side of the pig's body as reader) had greater detection percentage compared to the left (80.5 % and 7

关键词： Modulation   Backscatter   Symbols   Sensitivity   Amplitude shift keying   Reflection coefficient   Frequency shift keying   ASK   backscatter communication   energy harvesting   optimization   power maximization   reflection coefficient   RFID  

摘要： This paper studies backscatter communication (BackCom) systems with a passive backscatter tag. The effectiveness of these tags is limited by the amount of energy they can harness from incident radio signals, which are used to backscatter information through the modulation of reflections. To address this limitation, we adopt a practical Constant-Linear-Constant (CLC) energy harvesting model that accounts for the harvester's sensitivity and saturation threshold, both of which depend on the input power. This paper aims to maximize this harvested power at a passive tag by optimally designing the underlying M-ary amplitude-shift keying (ASK) modulator in a monostatic BackCom system. Specifically, we derive the closed-form expression for the global optimal reflection coefficients that maximize the tag's harvested power while satisfying the minimum symbol error rate (SER) requirement, tag sensitivity, and reader sensitivity constraints. We also proposed optimal binary-ASK modulation design to gain novel design insights on practical BackCom systems with readers having superior sensitivity. We have validated these nontrivial analytical claims via extensive simulations. The numerical results provide insight into the impact of the transmit symbol probability, tag sensitivity constraint, and SER on the maximum average harvested power. Remarkably, our design achieves an overall gain of around 13% over the benchmark, signifying its utility in improving the efficiency of BackCom systems. Moreover, our proposed solution methodology for determining the maximum average harvested power is applicable to any type of energy harvesting model that exhibits a monotonic increasing relationship with the input power.

关键词： IoMT   Cryptanalysis   RFID   Authentication   Healthcare  

摘要： In the environment of Internet of Medical Things (IoMT), RFID (Radio Frequency Identification)systems are already widely used for identification and authentication for important objects such as patient or medical equipment. Recently Kumar et al. proposed a mutual RFID authentication scheme for healthcare systems. They claimed that their scheme realized mutual authentication between tag and reader, and can resist to known attacks. In this article, we analyze the security of the protocol and point out three security weaknesses: the failure of bidirectional authentication and the inability to resist impersonate and de- synchronization attacks. The simulation results of the attack also show that their protocol fails to meet the security requirements of the Healthcare systems. Therefore, we propose a new improved RFID bidirectional authentication protocol to amend the security vulnerabilities in Kumar et al. 's protocol. The proposed protocol is also simulated, and finally we compare the proposed protocol with other similar protocols in terms of security and performance, the results show that our proposed protocol is preferable for medical system.

关键词： sensors   soft wearable robotics   monitors   design  

摘要： Real-time measurement of head rotation, a primary human body movement, offers potential advantages in rehabilitating head or neck motor disorders, promoting seamless human-robot interaction, and tracking the lateral glance of children with autism spectrum disorder for effective intervention. However, existing options such as cameras capturing the entire face or skin-attached sensors have limitations concerning privacy, safety, and/or usability. This research introduces a novel method that employs a battery-free RFID tag-based wearable sensor for monitoring head orientation, as a substitute for the existing options like camera. By attaching a pair of passive RFID tags to the front of the head at a specific distance from each other, the signal strength of each tag within the pair differs based on the discrepancy in distance from the RFID reader caused by head rotation. Important parameters including distance between the tags, distance from the reader, and tag types, are investigated to suggest optimal sensor design. In tests involving random head rotations by 10 healthy adults, there was a significant correlation between the orientation of the head and gaze in the yaw direction and the differences in signal strength from the sensor pairs. The correlation coefficients ( $ {r}<^>2 $ ) were satisfactory, at 0.88 for head and 0.83 for left eye pupil orientations. However, the sensor failed to estimate pitch rotations for head and gaze, due to the insufficient vertical spacing between the tags. No demographic factors appeared to influence the results.

关键词： Radio frequency identification   received signal strength indicator   deep Q learning   adaptive emperor penguin colony optimizer   indoor localization  

摘要： Radio Frequency Identification (RFID) is exploited for localizing objects in an indoor environment. Indoor localization is a critical component of various applications, ranging from smart homes to industrial automation. Traditional methods often suffer from limitations in accuracy and scalability. The existing models found it complex to develop a map approach of the tag received signal strength indicator (RSSI) and the distance of the tag and reader in an indoor nature. This work presents an enhanced model that integrates RFID technology using deep Q learning (DQL) and adaptive emperor penguin colony optimizer (AEPCO) for improving the relationship between tag position and RFID signals. By utilizing RFID tags and readers, spatial data are collected and then processed through a proposed DQL-AEPCO designed to accurately estimate positions within indoor environments. Moreover, for enhancing the training quality, the dataset pre-processed using Gaussian filtering (GF) is presented for eliminating RSSI faults. The demonstration proved that the suggested DQL-AEPCO can able to locate the multi-tags with high stability and robustness and outperformed the conventional models.

关键词： Concrete Monitoring   Structural Health Monitoring   UHF antenna   Sensor   Additive manufacturing   RFID  

摘要： This paper introduces a novel encapsulated 3D-printed UHF antenna system for early-stage and long-term concrete monitoring. Our goal is to leverage the capacities of additive manufacturing techniques to enhance antenna performance. We design and implement an encapsulated biconical geometry to mitigate medium losses due to being placed within concrete, to improve radiative efficiency, and to ensure stable antenna impedance. Various antenna prototypes were designed, optimized, fabricated, and characterized via laboratory and mortar sample measurements. We succeeded in integrating our novel system with existing temperature and humidity sensors, and interfaced it with an automatic data acquisition system for continuous concrete monitoring. Comparison with previous acquisition systems was performed. Herein, we present the design process, laboratory characterization, and field testing, including three case studies. Significant efforts were made to miniaturize the antenna while maintaining performance. Full system integration is demonstrated. Measurements were taken from antennas buried at depths of up to 30 cm;they showed good performance from an early start and up to longterm operation. These promising results confirm that improved antenna design and proper encapsulation can enhance system performance, especially in challenging and dynamic environments such as concrete.