Sensors, Vol. 19, Pages 4061: GNSS/LiDAR-Based Navigation of an Aerial Robot in Sparse Forests

Sensors, Vol. 19, Pages 4061: GNSS/LiDAR-Based Navigation of an Aerial Robot in Sparse Forests Sensors doi: 10.3390/s19194061 Authors: Antonio C. B. Chiella Henrique N. Machado Bruno O. S. Teixeira Guilherme A. S. Pereira Autonomous navigation of unmanned vehicles in forests is a challenging task. In such environments, due to the canopies of the trees, information from Global Navigation Satellite Systems (GNSS) can be degraded or even unavailable. Also, because of the large number of obstacles, a previous detailed map of the environment is not practical. In this paper, we solve the complete navigation problem of an aerial robot in a sparse forest, where there is enough space for the flight and the GNSS signals can be sporadically detected. For localization, we propose a state estimator that merges information from GNSS, Attitude and Heading Reference Systems (AHRS), and odometry based on Light Detection and Ranging (LiDAR) sensors. In our LiDAR-based odometry solution, the trunks of the trees are used in a feature-based scan matching algorithm to estimate the relative movement of the vehicle. Our method employs a robust adaptive fusion algorithm based on the unscented Kalman filter. For motion control, we adopt a strategy that integrates a vector field, used to impose the main direction of the movement for the robot, with an optimal probabilistic planner, which is responsible for obstacle avoidance. Experiments with a quadrotor equipped with a planar LiDAR in an...
Source: Sensors - Category: Biotechnology Authors: Tags: Article Source Type: research

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Source: Sport Management Review - Category: Sports Medicine Source Type: research
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Publication date: Available online 14 October 2019Source: NeuroImage: ClinicalAuthor(s): Robert Loughnan, Diego L. Lorca-Puls, Andrea Gajardo-Vidal, Valeria Espejo-Videla, Céline R. Gillebert, Dante Mantini, Cathy J. Price, Thomas M.H. HopeAbstractAround a third of stroke survivors suffer from acquired language disorders (aphasia), but current medicine cannot predict whether or when they might recover. Prognostic research in this area increasingly draws on datasets associating structural brain imaging data with outcome scores for ever-larger samples of stroke patients. The aim is to learn brain-behavior trends from ...
Source: NeuroImage: Clinical - Category: Radiology Source Type: research
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Source: Investigative Radiology - Category: Radiology Tags: Original Articles Source Type: research
Objectives The aim of this study was to compare a compressed-sensing free-breathing VIBE (fbVIBE) with a conventional breath-hold VIBE (bhVIBE) for dynamic contrast-enhanced imaging of the upper abdomen. Materials and Methods In total, 70 datasets (bhVIBE, n = 30; fbVIBE n = 40; hard-gated [hg] reconstruction, n = 30; motion-state-resolved [mr] reconstruction, n = 10) were assessed by 2 experienced readers. Both sequences were performed on 1.5-T magnetic resonance imaging scanners. The prototypical fbVIBE sequence acquired a navigation signal along with the imaging data and supported 2 different reconstructions: an hg...
Source: Investigative Radiology - Category: Radiology Tags: Original Articles Source Type: research
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Source: Journal of Clinical Orthopaedics and Trauma - Category: Orthopaedics Source Type: research
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Source: Journal of Minimally Invasive Gynecology - Category: OBGYN Source Type: research
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Source: Journal of Minimally Invasive Gynecology - Category: OBGYN Source Type: research
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Source: The Lancet - Category: General Medicine Source Type: research
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