Self-Localization of Ultra-Wideband Anchors: From Theory to Practice

Abstract

Ultra-wideband (UWB) radios are increasingly exploited for localization in complex deployments with tens or even hundreds of anchor nodes, whose position must be measured accurately: a long and error-prone <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">manual</i> chore. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Self-localization</i> techniques can estimate anchor positions <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">automatically</i> , from relative distances acquired via UWB, but are often evaluated i) only with a handful of anchors all in range, a far cry from the large, multi-hop setups above, and ii) in simulation, therefore neglecting <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">system</i> aspects and undermining immediate use in real contexts. We tackle the problem from a different, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">practical</i> viewpoint. First, we exploit <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">three real-world, large-scale, multi-hop UWB testbeds</i> , a unique asset in the literature. Second, we build upon state-of-the-art multidimensional scaling (MDS) that, unlike recent UWB-based techniques, is not limited to a specific type of localization or infrastructure, is computationally lightweight, and does not require training. Third, we integrate MDS with in-field distance estimation, yielding a complete, immediately usable self-localization system. Our evaluation, both in simulation and in the testbeds above, analyzes extensively the parameter space (e.g., the impact of ranging errors or anchor connectivity) and shows that anchor positions are determined quickly and accurately, minimizing manual labor without significant detriment to the accuracy of the localization system relying on them.