Passive wireless tags for tongue controlled assistive technology interfaces

Tongue control with low profile, passive mouth tags is demonstrated as a human–device interface by communicating values of tongue-tag separation over a wireless link. Confusion matrices are provided to demonstrate user accuracy in targeting by tongue position. Accuracy is found to increase dramatically after short training sequences with errors falling close to 1% in magnitude with zero missed targets. The rate at which users are able to learn accurate targeting with high accuracy indicates that this is an intuitive device to operate. The significance of the work is that innovative very unobtrusive, wireless tags can be used to provide intuitive human–computer interfaces based on low cost and disposable mouth mounted technology. With the development of an appropriate reading system, control of assistive devices such as computer mice or wheelchairs could be possible for tetraplegics and others who retain fine motor control capability of their tongues. The tags contain no battery and are intended to fit directly on the hard palate, detecting tongue position in the mouth with no need for tongue piercings

Passive Automatic Identification System for Maritime Surveillance

This work describes the main achievements in the Passive AIS (P-AIS) project stage. The extensive literature research in the second chapter concludes performing additional in-situ experiments to estimate reliable target RCS and clutter reflectivity values at the AIS frequency range. The typical effective RCS distribution for ferry, yacht and small wooden boat is experimentally drawn; it reaches up to 26dBsm for the ferry. A clutter model is created, taking into account the literature and the experimental study. The AIS signal waveform is analyzed and the potential range and Doppler resolution is defined. More specifically, the signal ambiguity function gives approximately 20km of range resolution and 40Hz Doppler resolution. A coverage prediction tool, based on the bistatic radar equation, including the aforementioned clutter model; bistatic geometry theory; the effective target RCS; the antenna pattern; the AIS air interface parameters is made. The tool estimates the possible P-AIS coverage area. The work concludes that: even in case of high sea state, the sea is considered as a smooth surface reflection for low grazing angle of observation in the VHF range; the equidistant SNR areas change from Cassini shape to single oval receiver centered; the AIS energy provides excellent target “visibility” if the clutter is not considered. Discussions for further clutter reduction and system sophistication are arisen.JRC.G.4-Maritime affair

Virtual Guide System

The Virtual Tour Guide is like an ordinary audio guide that you see in museums with a video component built into it. The completed project consists of a hardware/software RFID module and a purely software iTouch module. The user carries an iTouch which has a GUI running on it. On the back of the iTouch is attached an RFID tag. Outside each exhibit shall be an RFID antenna which the user must swipe the tag at. The antenna recognizes the tag and communicates its location and the tag\u27s unique ID to the GUI on the iTouch. The GUI then switches to a page corresponding to the location it is at. The user can then chose to view videos detailing about that exhibit. Once satisfied, the user can hit the done button, and walk to the next exhibit starting the entire process again

Wireless Positioning and Tracking for Internet of Things in GPS-denied Environments

Wireless positioning and tracking have long been a critical technology for various applications such as indoor/outdoor navigation, surveillance, tracking of assets and employees, and guided tours, among others. Proliferation of Internet of Things (IoT) devices, the evolution of smart cities, and vulnerabilities of traditional localization technologies to cyber-attacks such as jamming and spoofing of GPS necessitate development of novel radio frequency (RF) localization and tracking technologies that are accurate, energy-efficient, robust, scalable, non-invasive and secure. The main challenges that are considered in this research work are obtaining fundamental limits of localization accuracy using received signal strength (RSS) information with directional antennas, and use of burst and intermittent measurements for localization. In this dissertation, we consider various RSS-based techniques that rely on existing wireless infrastructures to obtain location information of corresponding IoT devices. In the first approach, we present a detailed study on localization accuracy of UHF RF IDentification (RFID) systems considering realistic radiation pattern of directional antennas. Radiation patterns of antennas and antenna arrays may significantly affect RSS in wireless networks. The sensitivity of tag antennas and receiver antennas play a crucial role. In this research, we obtain the fundamental limits of localization accuracy considering radiation patterns and sensitivity of the antennas by deriving Cramer-Rao Lower Bounds (CRLBs) using estimation theory techniques. In the second approach, we consider a millimeter Wave (mmWave) system with linear antenna array using beamforming radiation patterns to localize user equipment in an indoor environment. In the third approach, we introduce a tracking and occupancy monitoring system that uses ambient, bursty, and intermittent WiFi probe requests radiated from mobile devices. Burst and intermittent signals are prominent characteristics of IoT devices; using these features, we propose a tracking technique that uses interacting multiple models (IMM) with Kalman filtering. Finally, we tackle the problem of indoor UAV navigation to a wireless source using its Rayleigh fading RSS measurements. We propose a UAV navigation technique based on Q-learning that is a model-free reinforcement learning technique to tackle the variation in the RSS caused by Rayleigh fading

Hydroacoustic Analysis of the Effects of a Tidal Power Turbine on Fishes

Tidal currents help shape coastal marine environments and are essential in life cycles of many fish species. Areas with strong tidal currents are also targeted by humans for energy extraction via tidal energy turbines. The effects of these devices on fishes are difficult to predict because fish behavior within fast tidal currents is largely unstudied. Based at a tidal energy site in Cobscook Bay, Maine, this work sought to describe fish reactions to a tidal energy device, to understand the natural presence of fish at the site, and to provide guidance for future monitoring of tidal energy device effects in these difficult environments. A bottom-mounted echosounder was used to monitor the behavior of fish 7-18 m away from a stationary MHK device for several weeks. Fish moved with the current, but those approaching the device showed signs of avoiding it by adjusting their direction. The same echosounder was used to collect a two-year record of hourly fish passage rate at the depth of the turbine, after it had been removed. Fish passage rate, and therefore potential encounter rate with the turbine, changed dramatically over time with the dominant environmental patterns (tidal, daily, lunar, and seasonal cycles). By timing surveys of fish abundance at tidal energy sites with these cycles (e.g., carrying out 24-hr surveys at the same lunar stage throughout the year), the quality of results can be improved. Using this approach at tidal energy sites could therefore increase our ability to detect device effects without requiring expensive continuous sampling over a long time. Monitoring costs may be further reduced by using single beam echosounders, rather than the typical split beam systems, as statistical methods (deconvolution) were found to make certain single beam data comparable to that from the split beam. Depending on monitoring goals, the use of single beam echosounders could substantially reduce costs while supplying sufficient information on device effects for use in management decisions. Results from Cobscook Bay are likely to be useful at other tidal energy sites, but study designs and results need to be considered in the context of fish species and life stages present

Sensor-based management systems based on RFID technology

Παρατηρήσεις έκδοσης: λείπουν οι σελίδες 78, 102 από το φυσικό τεκμήριο.In this diploma thesis, the RFID technology is analyzed (operating principles, readers' and tags hardware, coding, modulation, anticollision procedures, frequencies, standards, applications). Moreover, a protocol to synchronize readers working in a multi-reader multi-tag environment is proposed. The protocol is applied to the store shelf scanning application and further refined to meet the requirements of this specific application

Design, implementation, and characterisation of a novel lidar ceilometer

A novel lidar ceilometer prototype based on divided lens optics has been designed, built, characterised, and tested. The primary applications for this manufacturable ground-based sensor are the determination of cloud base height and the measurement of vertical visibility. First, the design, which was developed in order to achieve superior performance at a low cost, is described in detail, along with the process used to develop it. The primary design considerations of optical signal to noise ratio, range-dependent overlap of the transmitter and receiver channels, and manufacturability, were balanced to develop an instrument with good signal to noise ratio, fast turn-on of overlap for detection of close range returns, and a minimised number of optical components and simplicity of assembly for cost control purposes. Second, a novel imaging method for characterisation of transmitter-receiver overlap as a function of range is described and applied to the instrument. The method is validated by an alternative experimental method and a geometric calculation that is specific to the unique geometry of the instrument. These techniques allow the calibration of close range detection sensitivity in order to acquire information prior to full overlap. Finally, signal processing methods used to automate the detection process are described. A novel two-part cloud base detection algorithm has been developed which combines extinction-derived visibility thresholds in the inverted cloud return signal with feature detection on the raw signal. In addition, standard approaches for determination of visibility based on an iterative far boundary inversion method, and calibration of attenuated backscatter profile using returns from a fully-attenuating water cloud, have been applied to the prototype. The prototype design, characterisation, and signal processing have been shown to be appropriate for implementation into a commercial instrument. The work that has been carried out provides a platform upon which a wide range of further work can be built

Ultra high frequency (UHF) radio-frequency identification (RFID) for robot perception and mobile manipulation

Personal robots with autonomy, mobility, and manipulation capabilities have the potential to dramatically improve quality of life for various user populations, such as older adults and individuals with motor impairments. Unfortunately, unstructured environments present many challenges that hinder robot deployment in ordinary homes. This thesis seeks to address some of these challenges through a new robotic sensing modality that leverages a small amount of environmental augmentation in the form of Ultra High Frequency (UHF) Radio-Frequency Identification (RFID) tags. Previous research has demonstrated the utility of infrastructure tags (affixed to walls) for robot localization; in this thesis, we specifically focus on tagging objects. Owing to their low-cost and passive (battery-free) operation, users can apply UHF RFID tags to hundreds of objects throughout their homes. The tags provide two valuable properties for robots: a unique identifier and receive signal strength indicator (RSSI, the strength of a tag's response). This thesis explores robot behaviors and radio frequency perception techniques using robot-mounted UHF RFID readers that enable a robot to efficiently discover, locate, and interact with UHF RFID tags applied to objects and people of interest. The behaviors and algorithms explicitly rely on the robot's mobility and manipulation capabilities to provide multiple opportunistic views of the complex electromagnetic landscape inside a home environment. The electromagnetic properties of RFID tags change when applied to common household objects. Objects can have varied material properties, can be placed in diverse orientations, and be relocated to completely new environments. We present a new class of optimization-based techniques for RFID sensing that are robust to the variation in tag performance caused by these complexities. We discuss a hybrid global-local search algorithm where a robot employing long-range directional antennas searches for tagged objects by maximizing expected RSSI measurements; that is, the robot attempts to position itself (1) near a desired tagged object and (2) oriented towards it. The robot first performs a sparse, global RFID search to locate a pose in the neighborhood of the tagged object, followed by a series of local search behaviors (bearing estimation and RFID servoing) to refine the robot's state within the local basin of attraction. We report on RFID search experiments performed in Georgia Tech's Aware Home (a real home). Our optimization-based approach yields superior performance compared to state of the art tag localization algorithms, does not require RF sensor models, is easy to implement, and generalizes to other short-range RFID sensor systems embedded in a robot's end effector. We demonstrate proof of concept applications, such as medication delivery and multi-sensor fusion, using these techniques. Through our experimental results, we show that UHF RFID is a complementary sensing modality that can assist robots in unstructured human environments.PhDCommittee Chair: Kemp, Charles C.; Committee Member: Abowd, Gregory; Committee Member: Howard, Ayanna; Committee Member: Ingram, Mary Ann; Committee Member: Reynolds, Matt; Committee Member: Tentzeris, Emmanoui

Radio wave propagation through the ionosphere

The non-transient plasma that is closest to Earth is found in the ionosphere at altitudes above approximately 60 km. It is observed either by ground-based, in-situ, or space-borne instrumentation and utilized to study and determine plasma phenomena and dynamics and the near-Earth space. Through active modification experiments, transmitting high-power, high-frequency radio waves into the ionospheric plasma, the interaction between waves and particles in a plasma can be studied in controllable and repeatable experiments. The transmitted radio wave is usually assumed to propagate either in the left-handed O mode or right-handed X mode. When encountering the respective cutoff or reflection condition in the ionosphere, the incident wave is reflected and does not propagate further into the ionospheric plasma. However, multiple experiments show that transionospheric wave propagation, beyond the reflection altitude and to the topside ionosphere, is possible for certain conditions. This thesis investigates the conditions and characteristics of transionospheric wave propagation in the polar ionosphere. Multiple experiments conducted at the EISCAT facilities near Tromsø, were performed transmitting an O-mode wave in the magnetic zenith direction. The findings show evidence of the incident wave propagating beyond its cutoff altitude and continuing propagation. Systematically recurring enhancements of the ion line spectra, generated by the modification wave, at the topside ionosphere are presented, as well as electron temperature enhancements consistent with wave propagation to higher altitudes. Further, a method for determining the electron density to a higher accuracy than previously achieved, has been developed. This permitted the calculation of altitude profiles of the plasma- , upper hybrid- , and multiple cutoff frequencies, enabling the identification of two separate cases of topside ion line enhancements. With this, a gyroharmonic effect at the top- and bottomside ionosphere has been identified for both cases, as well as the characteristics of transionospheric wave propagation. The observations are consistent with wave propagation in the L mode rather than the O mode. This thesis suggests a plausible propagation process and discusses the involved plasma processes. The results firmly establish the possibility of transionospheric wave propagation outside the standard radio window and thus expand our current understanding of wave-particle interaction and wave propagation in a plasma