Positioning Techniques with Smartphone Technology: Performances and Methodologies in Outdoor and Indoor Scenarios

Smartphone technology is widespread both in the academy and in the commercial world. Almost every people have today a smartphone in their pocket, that are not only used to call other people but also to share their location on social networks or to plan activities. Today with a smartphone we can compute our position using the sensors settled inside the device that may also include accelerometers, gyroscopes and magnetometers, teslameter, proximity sensors, barometer, and GPS/GNSS chipset. In this chapter we want to analyze the state-of-the-art of the positioning with smartphone technology, considering both outdoor and indoor scenarios. Particular attention will be paid to this last situation, where the accuracy can be improved fusing information coming from more than one sensor. In particular, we will investigate an innovative method of image recognition based (IRB) technology, particularly useful in GNSS denied environment, taking into account the two main problems that arise when the IRB positioning methods are considered: the first one is the optimization of the battery, that implies the minimization of the frame rate, and secondly the latencies due to image processing for visual search solutions, required by the size of the database with the 3D environment images

Towards secure & robust PNT for automated systems

This dissertation makes four contributions in support of secure and robust position, navigation, and timing (PNT) for automated systems. The first two relate to PNT security while the latter two address robust positioning for automated ground vehicles. The first contribution is a fundamental theory for provably-secure clock synchronization between two agents in a distributed automated system. All one-way synchronization protocols, such as those based on the Global Positioning System (GPS) and other Global Navigation Satellite Systems (GNSS), are shown to be vulnerable to man-in-the-middle delay attacks. This contribution is the first to identify the necessary and sufficient conditions for provably secure clock synchronization. The second contribution, also related to PNT security, is a three-year study of the world-wide GPS interference landscape based on data from a dual-frequency GNSS receiver operating continuously on the International Space Station (ISS). This work is the first publicly-reported space-based survey of GNSS interference, and unveils previously-unreported GNSS interference activity. The third contribution is a novel ground vehicle positioning technique that is robust to GNSS signal blockage, poor lighting conditions, and adverse weather events such as heavy rain and dense fog. The technique relies on sensors that are commonly available on automated vehicles and are insensitive to lighting and inclement weather: automotive radar, low-cost inertial measurement units (IMUs), and GNSS. Remarkably, it is shown that, given a prior radar map, the proposed technique operating on data from off-the-shelf all-weather automotive sensors can maintain sub-50-cm horizontal position accuracy during 60 min of GNSS-denied driving in downtown Austin, TX. This dissertation’s final contribution is an analysis and demonstration of the feasibility of crowd-sourced digital mapping for automated vehicles. Localization techniques, such as the one described in the previous contribution, rely on such digital maps for accuracy and robustness. A key enabler for large-scale up-to-date maps is enlisting the help of the very consumer vehicles that need the map to build and update it. A method for fusing multi-session vision data into a unified digital map is developed. The asymptotic limit of such a map’s globally-referenced position accuracy is explored for the case in which the mapping agents rely on low-cost GNSS receivers performing standard code-phase-based navigation. Experimental validation along a semi-urban route shows that low-cost consumer vehicles incrementally tighten the accuracy of the jointly-optimized digital map over time enough to support sub-lane-level positioning in a global frame of reference.Electrical and Computer Engineerin

Development of a new device for the measurement and modeling of an innovative risk index for cultural heritage application

The monitoring, as a function of time, of environmental parameters in cultural heritage is essential to preserve materials, to recognize the reasons of degradation and to evaluate their effects. The degrading effects of objects in cultural heritage field, can be classified in optical, morphological, physical-chemical/mechanical and alterations and depend by micro-climatic conditions. For this reason, in recent years, several solutions have been developed and commercialized for environmental monitoring, some compatible with general advice and others OEM (Original Equipment Manufacturing). However, the trend of application between compliant and non-ISO-compliant devices has not yet been sufficiently analyzed. In this first section, we show how in the last ten years researchers have shifted their attention to custom-made devices based on new generation sensors despite the expense of units ISO certified. The study based on a review of scientific articles has shown that: with the increase of low-cost and open-source technologies applied in the Environmental Impact Assessment (EIA) and in particular in the cultural heritage, led to a research advancement in the field, but, at the same time, increased non-homogeneity of the methods, impinging comparability of results. In recent years the trend is to use low-cost automatic wireless systems. This innovation, however, opens new scenarios and challenges on how to improve their stability, longevity, and sensitivity; reduce maintenance (battery replacement, including calibration or sensors); improve data analysis/management/display costs. In particular, it has highlighted the current difficulty of low-cost detectors to satisfy the robustness and reliability of regulatory and conventional stationary monitors at the expense of the periods and aesthetics. We have therefore paid particular attention to the sensitivity and reliability of the innovative solutions presented to overcome the traditional limitations, as well as to the real feasibility of solutions regarding sustainability, adaptability to the works of art or price. We also see the need for more communication between the scientific community and the decision-makers, who have only recently opened up to this paradigm. We highlighted the need to identify recurrent or innovative topics in the various documents concerning the approaches to preventive conservation, the preservation of damage and environmental management. After a review of state of the art regarding the different sampling device applied in cultural heritage and a survey of the parameters that involve a degradation effect on the materials, in this section, we focus our attention on a sensors-based prototype able to detect: (i) temperature and relative humidity; (ii) NO, NO2 and SO2; (iii) vibrations. In particular, this section describes the design and the validation of the Wireless Sensor Network (WSN) propose3, named WENDY, an acronym for Wireless Environmental moNitoring Device prototYpe. WENDY, built on a microcontroller of ATmega328P series, gathers signals from a sensor for temperature and relative humidity; a 9-axis MIMU; and three gas detection miniature boards (NO, NO2 and SO2). Complete the board a connector for memory card (SD) and an RTC. Additionally, a module based on the ZigBee standard could be used to transmit all data. In this section, precisely, we present the performances of the WSN node in detecting: structure tilt, vibrations and the daily cycle of humidity, temperature and gas deposition. The experimental setup used to evaluate the accuracy of MIMU system highlighted a relative error on shock acceleration measurement, in term of normalized root mean square error, lower than 0.1 % for the sinusoidal input and 0.51 % for cardinal sin input, with an average accuracy in the principal peak reconstruction of 1 % in the chosen frequency range (5 Hz to 50 Hz). The MIMU accuracy for tilt measurement, evaluated through the root mean square error was equal to 0.3° and a standard deviation always lower than 0.4° in the 0-90° tilt range. The gas detection and temperature/ humidity boards showed data comparable with the nearby certified ARPA system device. The aim of the applicative section is monitoring effects of different factors which affect the “Minerva Medica Temple,” an archeological site in Rome. In particular, we focus on: (i) the seasonal thermal variations on the structure; (ii) the contamination due to by local traffic regarding gaseous pollutant and (iii) the dynamic response of the structure to a tramway line located in Rome and called “Roma- Giardinetti.” The developed system allows for prioritization of intervention both for management and interventions planning, regarding restoration, consolidation, and conservation. Moreover, the software structure of the environmental monitoring device is presented and expounded in detail.4 Always in this section, an innovative procedure for the evaluation of the environmental hazard in cultural heritage is proposed. This risk assessment can be considered as a “relative risk assessment methodology.” In particular, it considers the impacts of microclimatic conditions on the monument, based on the international norms and the current scientific knowledge. For measurement campaigns with WENDY, the risk method proposed is applied to the results of two measurement campaigns carried out between 2017 and 2018 over two different periods (September-December and March-July), at “Minerva Medica Temple,” in Rome