2,760 research outputs found
LOCATE-US: Indoor Positioning for Mobile Devices Using Encoded Ultrasonic Signals, Inertial Sensors and Graph- Matching
Indoor positioning remains a challenge and, despite much research and development carried out in the last decade, there is still no standard as with the Global Navigation Satellite Systems (GNSS) outdoors. This paper presents an indoor positioning system called LOCATE-US with adjustable granularity for use with commercial mobile devices, such as smartphones or tablets. LOCATE-US is privacy-oriented and allows every device to compute its own position by fusing ultrasonic, inertial sensor measurements and map information. Ultrasonic Local Positioning Systems (ULPS) based on encoded signals are placed in critical zones that require an accuracy below a few decimeters to correct the accumulated drift errors of the inertial measurements. These systems are well suited to work at room level as walls confine acoustic waves inside. To avoid audible artifacts, the U-LPS emission is set at 41.67 kHz, and an ultrasonic acquisition module with reduced dimensions is attached to the mobile device through the USB port to capture signals. Processing in the mobile device involves an improved Time Differences of Arrival (TDOA) estimation that is fused with the measurements from an external inertial sensor to obtain real-time location and trajectory display at a 10 Hz rate. Graph-matching has also been included, considering available prior knowledge about the navigation scenario. This kind of device is an adequate platform for Location-Based Services (LBS), enabling applications such as augmented reality, guiding applications, or people monitoring and assistance. The system architecture can easily incorporate new sensors in the future, such as UWB, RFiD or others.Universidad de AlcalĂĄJunta de Comunidades de Castilla-La ManchaAgencia Estatal de InvestigaciĂł
Review of UAV positioning in indoor environments and new proposal based on US measurements
Este documento se considera que es una ponencia de congresos en lugar de un capĂtulo de libro.10th International Conference on Indoor Positioning and Indoor Navigation (IPIN 2019) Pisa, Italy, September 30th - October 3rd, 2019The use of unmanned aerial vehicles (UAVs) has increased dramatically in recent years because of their huge potential in both civil and military applications and the decrease in prize of UAVs products. Location detection can be implemented through GNSS technology in outdoor environments, nevertheless its accuracy could be insufficient for some applications. Usability of GNSS in indoor environments is limited due to the signal attenuation as it cross through walls or the absence of line of sight. Considering the big market opportunity of indoor UAVs many researchers are devoting their efforts in the exploration of solutions for their positioning. Indoor UAV applications include location based services (LBS), advertisement, ambient assisted living environments or emergency response.
This work is an update survey in UAV indoor localization, so it can provide a guide and technical comparison perspective of different technologies with their main advantages and drawbacks. Finally, we propose an approach based on an ultrasonic local positioning system.Universidad de AlcalĂĄJunta de Comunidades de Castilla-La ManchaMinisterio de EconomĂa, Industria y Competitivida
Novel Approaches for Nondestructive Testing and Evaluation
Nondestructive testing and evaluation (NDT&E) is one of the most important techniques for determining the quality and safety of materials, components, devices, and structures. NDT&E technologies include ultrasonic testing (UT), magnetic particle testing (MT), magnetic flux leakage testing (MFLT), eddy current testing (ECT), radiation testing (RT), penetrant testing (PT), and visual testing (VT), and these are widely used throughout the modern industry. However, some NDT processes, such as those for cleaning specimens and removing paint, cause environmental pollution and must only be considered in limited environments (time, space, and sensor selection). Thus, NDT&E is classified as a typical 3D (dirty, dangerous, and difficult) job. In addition, NDT operators judge the presence of damage based on experience and subjective judgment, so in some cases, a flaw may not be detected during the test. Therefore, to obtain clearer test results, a means for the operator to determine flaws more easily should be provided. In addition, the test results should be organized systemically in order to identify the cause of the abnormality in the test specimen and to identify the progress of the damage quantitatively
High-rate acquisition system for an infrared LPS
2023 38th Conference on Design of Circuits and Integrated Systems (DCIS), 15-17 November 2023, MĂĄlaga, Spain.In the last years, the demand for positioning systems
based on visible light, infrared light or, in general, optical signals
has increased considerably due to their high accuracy and low
cost compared to positioning systems based on other technologies,
as well as their ease of integration due to their wide presence
in domestic and industrial environments. The main constraint
of these solutions is that the high speed of light makes the
acquisition process complex. This work proposes a complete
acquisition architecture for the twelve signals coming from four
QADA (Quadrature Angular Diversity Aperture) photoreceptors,
based on an analog front-end for signal conditioning at the input,
an analog-to-digital converter, and a final digital stage using an
FPGA for the acquisition of the data coming from the converter
with high data rates up to 16.25 Msps. To verify the system
performance, LS (Loosely Synchronized) sequences, often used
in positioning systems, are emitted by a LED, and, later, they
are acquired and digitally processed successfully by the proposed
architecture in some preliminary experimental tests.Agencia Estatal de InvestigaciĂłnUniversidad de AlcalĂĄJunta de Comunidades de Castilla-La ManchaEuropean Science Foundatio
Ultrasonic-Based Environmental Perception for Mobile 5G-Oriented XR Applications
One of the sectors that is expected to significantly benefit from 5G network deployment is eXtended Reality (XR). Besides the very high bandwidth, reliability, and Quality of Service (QoS) to be delivered to end users, XR also requires accurate environmental perception for safety reasons: this is fundamental when a user, wearing XR equipment, is immersed in a âvirtualâ world, but moves in a ârealâ environment. To overcome this limitation (especially when using low-cost XR equipments, such as cardboards worn by the end user), it is possible to exploit the potentialities offered by Internet of Things (IoT) nodes with sensing/actuating capabilities. In this paper, we rely on ultrasonic sensor-based IoT systems to perceive the surrounding environment and to provide âside informationâ to XR systems, then performing a preliminary experimental characterization campaign with different ultrasonic IoT system configurations worn by the end user. The combination of the information flows associated with XR and IoT components is enabled by 5G technology. An illustrative experimental scenario, relative to a âTourism 4.0â IoT-aided VR application deployed by Vodafone in Milan, Italy, is presented
Deep convolutional neural networks for estimating porous material parameters with ultrasound tomography
We study the feasibility of data based machine learning applied to ultrasound
tomography to estimate water-saturated porous material parameters. In this
work, the data to train the neural networks is simulated by solving wave
propagation in coupled poroviscoelastic-viscoelastic-acoustic media. As the
forward model, we consider a high-order discontinuous Galerkin method while
deep convolutional neural networks are used to solve the parameter estimation
problem. In the numerical experiment, we estimate the material porosity and
tortuosity while the remaining parameters which are of less interest are
successfully marginalized in the neural networks-based inversion. Computational
examples confirms the feasibility and accuracy of this approach
Multi-Sensor Methods for Mobile Radar Motion Capture and Compensation.
Ph.D. Thesis. University of HawaiÊ»i at MÄnoa 2017
CALIBRATION OF AN ULTRASONIC TRANSMISSIVE COMPUTED TOMOGRAPHY SYSTEM
Tato dizertace je zamÄĆena na medicĂnskou zobrazovacĂ modalitu â ultrazvukovou poÄĂtaÄovou tomografii â a algoritmy zlepĆĄujĂcĂ kvalitu zobrazenĂ, zejmĂ©na kalibraci USCT pĆĂstroje. USCT je novou modalitou kombinujĂcĂ ultrazvukovĂœ pĆenos signĂĄlĆŻ a principy tomografickĂ© rekonstrukce obrazĆŻ vyvĂjenĂœch pro jinĂ© tomografickĂ© systĂ©my. V principu lze vytvoĆit kvantitativnĂ 3D obrazovĂ© objemy s vysokĂœm rozliĆĄenĂm a kontrastem. USCT je primĂĄrnÄ urÄeno pro diagnĂłzu rakoviny prsu. Autor spolupracoval na projektu Institutu ZpracovĂĄnĂ dat a Elektroniky, Forschungszentrum Karlsruhe, kde je USCT systĂ©m vyvĂjen. Jeden ze zĂĄsadnĂch problĂ©mĆŻ prototypu USCT v Karlsruhe byla absence kalibrace. TisĂce ultrazvukovĂœch mÄniÄĆŻ se liĆĄĂ v citlivosti, smÄrovosti a frekvenÄnĂ odezvÄ. Tyto parametry jsou navĂc promÄnnĂ© v Äase. DalĆĄĂ a mnohem zĂĄvaĆŸnÄjĆĄĂ problĂ©m byl v poziÄnĂch odchylkĂĄch jednotlivĂœch mÄniÄĆŻ. VĆĄechny tyto aspekty majĂ vliv na koneÄnou kvalitu rekonstruovanĂœch obrazĆŻ. ProblĂ©m kalibrace si autor zvolil jako hlavnĂ tĂ©ma dizertace. Tato dizertace popisuje novĂ© metody v oblastech rekonstrukce ĂștlumovĂœch obrazĆŻ, kalibrace citlivosti mÄniÄĆŻ a zejmĂ©na geometrickĂĄ kalibrace pozic mÄniÄĆŻ. Tyto metody byly implementovĂĄny a otestovĂĄny na reĂĄlnĂœch datech pochĂĄzejĂcĂch z prototypu USCT z Karlsruhe.This dissertation is centered on a medical imaging modality â the ultrasonic computed tomography (USCT) â and algorithms which improve the resulting image quality, namely the calibration of a USCT device. The USCT is a novel imaging modality which combines the phenomenon of ultrasound and image reconstruction principles developed for other tomographic systems. It is capable of producing quantitative 3D image volumes with high resolution and tissue contrast and is primarily aimed at breast cancer diagnosis. The author was involved in a joint research project at the Institute of Data Processing and Electronics, Forschungszentrum Karlsruhe (German National Research Center), where a USCT system is being developed. One of the main problems in the Karlsruhe USCT prototype was the absence of any calibration. The thousands of transducers used in the system have deviations in sensitivity, directivity, and frequency response. These parameters change over time as the transducers age. Also the mechanical positioning of the transducer elements is not precise. All these aspects greatly affect the overall quality of the reconstructed images. The problem of calibration of a USCT system was chosen as the main topic for this dissertation. The dissertation thesis presents novel methods in the area of reconstruction of attenuation images, sensitivity calibration, and mainly geometrical calibration. The methods were implemented and tested on real data generated by the Karlsruhe USCT device.
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