The practical feasibility of using RFID in a metal environment

Passive Radio Frequency Identification (RFID) has revolutionized the way in which products are identified. This paper considers the effect of metals on the performance of RFID at ultra high frequency (UHF). The paper establishes read patterns in space, highlighting the interference of RF waves due to three different metals, one ferrous and the other two non ferrous, when placed behind a transponder. The effect of thickness of the metal plate is also examined. Different metals have been found to have different interference effects although there are some similarities in their read patterns related to their material properties. Also experiments have been carried out to identify and establish various methods of improving this performance. Finally, differences between performance-measuring parameters, namely attenuating transmitted power and calculating read rate at a fixed attenuation are established and possible reasons of these observations are presented

Wireless Corrosion Monitoring for Reinforced Concrete Structures and Concrete Repair

Substantial efforts are put in preservation projects, but often little care is given once the project is finished. How do we know when we need to go back and repair the building again? A long-term monitoring system can provide invaluable information about the conditions of a building and building materials. Such information may help owners, architects, engineers and conservators to understand what the cause of the problem is, when and where the repair is needed, and what type of intervention is necessary. This can help prevent small problems from becoming large problems. This thesis will evaluate wireless monitoring systems for reinforced concrete structures. Using wireless sensors as monitoring devices is not a new technique. In fact, there are already several wireless sensors being used to monitor various types of structures, materials and conditions. However, most of the existing wireless sensors have short service lives due to limited battery capacity and issues with durability. This thesis research focuses on prototyping and evaluating a wireless and battery-less sensing device named Intelligent Aggregate (IA) and Intelligent Aggregate System (IAS). Intelligent Aggregate is based on the technology of passive RFID (Radio Frequency Identification) tags, which can wirelessly communicate with RFID readers through Ultra High Frequency (UHF) electromagnetic waves emitted from the readers. There are several advantages of using RFID devices over existing battery powered wireless sensors, which are bulky in size due to batteries and expensive to maintain due to the need to retrieve the sensors for occasional battery change. On the other hand, IA can operate as long as they can harvest energy from the RFID reader. Another advantage of using IA is the ability to easily and inexpensively build Wireless Sensing Networks (WSNs). By strategically deploying hundreds or thousands, if necessary, wireless sensing devices in a building, we can collect extensive information about the condition of buildings and materials in real-time. Such information would greatly help us to wisely use time, money, and other resources

Experimental feasibility study of a passive radio frequency identification-based distributed beamforming framework and radio frequency tag design for achieving dynamic beamforming

Passive UHF RFID tags works on the principle of backscattering mechanism. In realistic environment, there are multiple objects and tags that create complex, multipath propagation scenarios with numerous null-points, reduced read range and read rate. In general, the RF frontend of tags could be controlled such that the negative effects of multipath propagation are reduced or even inverted thus implementing a virtual beamforming. The theoretical framework of beamforming in RFID system, using additional tags as virtual antenna arrays, has been discussed before. The presented study evaluates the feasibility of such beamforming in passive RFID systems. Moreover, it synthesizes an appropriate propagation model that explains the experimental results and will aid in refining the beamforming scheme. Number of practical experiments has been carried out to validate the propagation models that were employed during the scheme design phase. The experimental results are presented and discussed. Although above method achieved increase in signal strength at certain locations, it had negative effect at remaining locations. Thus, a more dynamic beamforming would be required to achieve consistent increase in signal strength at all locations. Hence, above beamforming method is further extended to achieve dynamic beamforming. Method of dynamic beamforming is simulated and its results are discussed. Also, aspects of designing RF tag for achieving dynamic beamforming has been discussed --Abstract, page iv

Design and performance of a flexible metal mountable UHF RFID tag

The large number of requirements and opportunities for automatic identification in manufacturing domains such as automotive and electronics has accelerated the demand for item-level tracking using Radio Frequency IDentification technology (RFID). End-users are interested in solutions that enable a range of objects to be identified without changing the structure of the objects. Designing an RFID tag, which can be mounted successfully on metallic objects and meets the end-user requirement is a major research challenge. The aim of the research outlined in this paper is to determine the effects of the harsh manufacturing environments in which RFID tags are used and compare the performance of a range of RFID tag substrates that can be used to isolate the RFID tag antenna from metallic objects. The goal is to determine which substrates allow RFID tags to operate efficiently when attached to metallic, lossy or dielectric objects whilst being low cost, high performance, flexible and in some cases reusable solutions. A flexible RFID tag with a substrate consisting of an elastomer / polymer has been investigated as a part of this research. Additionally, paper and PET substrates integrated with a number of different conductive inks, have also been investigated as potential optimal solutions for the high volume manufacture of UHF RFID tags suitable for metal objects. The research details the design and evaluation of performance of number of RFID tags when applied to tracking of automotive assets and components such as stillages throughout their manufacturing, assembly and the supply chain

RFID Enabled Health Monitoring System for Aircraft Landing Gear

RFID has been used in the aviation industry to track and identify emergency equipment and other in-cabin assets on commercial aircraft for some time. Recently, the industry is looking to expand the use of RFID to more demanding parts and surfaces both inside and outside of an aircraft’s cabin, where RFID tags face much harsher conditions. The lLanding gear (LG) is one of the critical subsystems of an aircraft that plays an essential role in dispersing the energy of landing events and taxiing. Health monitoring of the LG has been suggested to help reduce both operational and maintenance costs, and extend the life of the LG beyond its current, fixed, designed service life. In this paper, we propose such a health monitoring system using a combination of active wired sensors and passive RFID tags. We present the measurement of UHF RFID tags on an aircraft landing gear using an aircraft-mounted fixed RFID reader. The results indicate that all major landing gear components and assemblies are shown to be identifiable by their EPC, and a 7 dB system margin has been achieved using 2 RFID reader antennas. Such a margin will tolerate degradations caused by harsh environments (e.g. low temperatures and high humidity) and enable update of information (e.g. flight count) to be stored on the RFID tags

Passive low frequency RFID for non-destructive evaluation and monitoring

Ph. D ThesisDespite of immense research over the years, defect monitoring in harsh environmental conditions still presents notable challenges for Non-Destructive Testing and Evaluation (NDT&E) and Structural Health Monitoring (SHM). One of the substantial challenges is the inaccessibility to the metal surface due to the large stand-off distance caused by the insulation layer. The hidden nature of corrosion and defect under thick insulation in harsh environmental conditions may result in it being not noticed and ultimately leading to failures. Generally electromagnetic NDT&E techniques which are used in pipeline industries require the removal of the insulation layer or high powered expensive equipment. Along with these, other limitations in the existing techniques create opportunities for novel systems to solve the challenges caused by Corrosion under Insulation (CUI). Extending from Pulsed Eddy Current (PEC), this research proposes the development and use of passive Low Frequency (LF) RFID hardware system for the detection and monitoring of corrosion and cracks on both ferrous and non-ferrous materials at varying high temperature conditions. The passive, low cost essence of RFID makes it an enchanting technique for long term condition monitoring. The contribution of the research work can be summarised as follows: (1) implementation of novel LF RFID sensor systems and the rig platform, experimental studies validating the detection capabilities of corrosion progression samples using transient feature analysis with respect to permeability and electrical conductivity changes along with enhanced sensitivity demonstration using ferrite sheet attached to the tag; (2) defect detection using swept frequency method to study the multiple frequency behaviour and further temperature suppression using feature fusion technique; (3) inhomogeneity study on ferrous materials at varying temperature and demonstration of the potential of the RFID system; (4) use of RFID tag with ceramic filled Poly-tetra-fluoro-ethyulene (PTFE) substrate for larger applicability of the sensing system in the industry; (5) lift-off independent defect monitoring using passive sweep frequency RFID sensors and feature extraction and fusion for robustness improvement. This research concludes that passive LF RFID system can be used to detect corrosion and crack on both ferrous and non-ferrous materials and then the system can be used to compensate for temperature variation making it useful for a wider range of applications. However, significant challenges such as permanent deployment of the tags for long term monitoring at higher temperatures and much higher standoff distance, still require improvement for real-world applicability.Engineering and Physical Sciences Research Council (EPSRC) CASE, National Nuclear Laboratory (NNL)

Helmsman, Set a Course : Using a Compass and RFID Tags for Indoor Localisation and Navigation

Localisation and navigation are still two of the most important issues in mobile robotics. In certain indoor application scenarios RFID (radio frequency identification)-based absolute localisation has been found to be especially successful in supporting navigation. In this paper we evaluate the feasibility of an RFID and compass based approach to robot localisation and navigation for indoor environments that are dominated by corridors. We describe our system and evaluate its performance in a small, but full-scale, test environment

Navigating the Corridors of Power : Using RFID and Compass Sensors for Robot Localisation and Navigation

Localisation and navigation are still of the most important issues in mobile robotics. In certain indoor application scenarios Radio frequency identification (RFID) based absolute localisation has been found to be especially successful in supporting navigation. In this paper we examine the feasibility of an RFID and compass based approach to robot localisation and navigation for indoor environments that are dominated by corridors. We present a proof of concept system and show how it can be used to localized within and navigate through an environment