108 research outputs found

    Patterns of use: how older adults with progressed dementia interact with a robot

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    Older adults represent a new user group of robots that are deployed in their private homes or in care facilities. In the presented study tangible aspects of older adults' interaction with an autonomous robot were focused. The robot was deployed as a companion in physical therapy for older adults with progressed dementia. Interaction was possible via a mounted touch screen. The menu was structured in a single layer and icons were big and with strong contrast. Employing a detailed observation protocol, interaction frequencies and contexts were assessed. Thereby, it was found that most of the interaction was encouraged by the therapists and that two out of 12 older adults with progressed dementia showed self-inducted interactions

    Geodetic Stereo SAR With Small Multi-Directional Radar Reflectors

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    This paper evaluates the applicability and achievable SAR accuracy for octahedrons – a combination of eight corner reflectors with a common phase centre. In an experiment at the observatory in Wettzell from July to November 2015 these cost-efficient and mobile radar targets were measured with TerraSAR-X Staring Spotlight and High-Resolution Spotlight. Applying the geodetic stereo SAR concept, octahedrons are very robust for absolute 3D positioning through their backscattering in multiple directions. Using octahedrons with as size of 47 cm, we achieve 3σ standard deviations of about 3 cm for east, north and height components. For individual measurements in Staring Spotlight the standard deviation shows 1.4 cm in range and 3.2 cm in azimuth

    What do staff in eldercare want a robot for? An assessment of potential tasks and user requirements for a long-term deployment

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    Robotic aids could help to overcome the gap between rising numbers of older adults and at the same time declining numbers of care staff. Assessments of end-user requirements, especially focusing on staff in eldercare facilities are still sparse. Contributing to this field of research this study presents end-user requirements and task analysis gained from a methodological combination of interviews and focus group discussions. The findings suggest different tasks robots in eldercare could engage in such as “fetch and carry” tasks, specific entertainment and information tasks, support in physical and occupational therapy, and in security. Furthermore this paper presents an iterative approach that closes the loop between requirements-assessments and subsequent implementations that follow the found requirements

    Potential of global SAR positioning for geodetic applications - Lessons learned from TerraSAR-X and Sentinel-1

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    With our implementation of geodetic techniques for data processing and data corrections, spaceborne Synthetic Aperture Radar (SAR) has attained the possibility of fixing global positions of dedicated radar points at the low centimeter accuracy level. Such points can be created by passive radar corner reflectors, and the positioning method relies on the inherent ranging capabilities of SAR sensors. Thus, we may refer to the method as SAR imaging geodesy or geodetic SAR. Determining accurate long-term global positions of objects on the Earth’s surface is typically associated with Global Navigation Satellite Systems (GNSS) and one of the core elements of modern space geodesy. In order to do so, high-grade geodetic equipment with constant power supply, as well as the possibility for data transfer are required, limiting dense application on a large scale and poses difficulties for very remote areas with little or no infrastructure. Whereas certain regions like Japan or the San Andreas Fault are densely covered by GNSS such coverage may not be achievable everywhere on the globe. To improve the situation, we present a concept of jointly using SAR and GNSS for expanding geodetic positioning to applications requiring long-term coordinate monitoring. In future, the use of cost-effective passive reflectors in X-band SAR or low-cost battery-powered active transponders, which are currently in development for C-band SAR, could provide global coordinates anywhere where SAR imagery is acquired under multiple incidence angles. The main requirements are precise orbit determination, processing of the SAR imagery omitting geometric approximations, as well as the rigorous correction of perturbations caused by atmospheric path delay and signals of the dynamic Earth. If a reflector or transponder already has known reference coordinates, e.g. from co-location with GNSS, the perturbing signals can be mitigated for the surrounding radar points by applying differential SAR positioning techniques similar to differential GNSS, provided that all the points are included in the same radar image. In this contribution we discuss the geodetic SAR methods with respect to our experiences gained with the TerraSAR-X mission, and present first results of experiments carried out with Sentinel-1 data

    Art dégénéré et spoliations des Juifs durant la Seconde Guerre mondiale

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    La dégénérescence fut une des grandes angoisses de l’Occident raciste et social-darwiniste. Le développement de la médecine et des sciences naturelles, le succès foudroyant de Darwin et la transposition des concepts darwiniens de la nature à la culture, de la faune à l’homme, mais aussi la confrontation avec des mondes extra-européens qui inquiétaient autant qu’ils fascinaient, puis le drame démographique de la (Très) Grande Guerre, amenèrent les grandes nations d’Europe et d’extrême-Europe (..

    In-depth verification of Sentinel-1 and TerraSAR-X geolocation accuracy using the Australian Corner Reflector Array

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    This article shows how the array of corner reflectors (CRs) in Queensland, Australia, together with highly accurate geodetic synthetic aperture radar (SAR) techniques—also called imaging geodesy—can be used to measure the absolute and relative geometric fidelity of SAR missions. We describe, in detail, the end-to-end methodology and apply it to TerraSAR-X Stripmap (SM) and ScanSAR (SC) data and to Sentinel-1interferometric wide swath (IW) data. Geometric distortions within images that are caused by commonly used SAR processor approximations are explained, and we show how to correct them during postprocessing. Our results, supported by the analysis of 140 images across the different SAR modes and using the 40 reflectors of the array, confirm our methodology and achieve the limits predicted by theory for both Sentinel-1 and TerraSAR-X. After our corrections, the Sentinel-1 residual errors are 6 cm in range and 26 cm in azimuth, including all error sources. The findings are confirmed by the mutual independent processing carried out at University of Zurich (UZH) and German Aerospace Center (DLR). This represents an improve�ment of the geolocation accuracy by approximately a factor of four in range and a factor of two in azimuth compared with the standard Sentinel-1 products. The TerraSAR-X results are even better. The achieved geolocation accuracy now approaches that of the global navigation satellite system (GNSS)-based survey of the CRs positions, which highlights the potential of the end-to-end SAR methodology for imaging geodesy

    Long Term Geodetic Monitoring Using Active C-Band Radar Transponders And Sentinel-1 - First Results

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    Reliable and accurate long term geodetic monitoring with SAR requires the installation of either passive corner reflectors or, alternatively smaller active devices. We report our first results using novel off-the-shelf transponders or electronic corner reflectors (ECRs) for geodetic measurements with Sentinel-1 C-band Synthetic Aperture Radar (SAR) data. For this purpose we set up a triangular arrangement consisting of one trihedral corner reflector and two active ECRs at the campus of German Aerospace Center (DLR) in Oberpfaffenhofen, Germany. We describe the practical aspects of such ECRs as well as first radiometric characteristics. Moreover, we present geometric accuracy numbers derived from imaging geodesy, i.e. absolute radargrammetric positioning, as well as from interferometric phase measurements
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