12 research outputs found
A Distributed Pipeline for Scalable, Deconflicted Formation Flying
Reliance on external localization infrastructure and centralized coordination
are main limiting factors for formation flying of vehicles in large numbers and
in unprepared environments. While solutions using onboard localization address
the dependency on external infrastructure, the associated coordination
strategies typically lack collision avoidance and scalability. To address these
shortcomings, we present a unified pipeline with onboard localization and a
distributed, collision-free motion planning strategy that scales to a large
number of vehicles. Since distributed collision avoidance strategies are known
to result in gridlock, we also present a decentralized task assignment solution
to deconflict vehicles. We experimentally validate our pipeline in simulation
and hardware. The results show that our approach for solving the optimization
problem associated with motion planning gives solutions within seconds in cases
where general purpose solvers fail due to high complexity. In addition, our
lightweight assignment strategy leads to successful and quicker formation
convergence in 96-100% of all trials, whereas indefinite gridlocks occur
without it for 33-50% of trials. By enabling large-scale, deconflicted
coordination, this pipeline should help pave the way for anytime, anywhere
deployment of aerial swarms.Comment: 8 main pages, 1 additional page, accepted to RA-L and IROS'2
A Synoptic- and Remote Sensing-based Analysis of a Severe Dust Storm Event over Central Asia
Published by [Verlag nicht ermittelbar], Taina
Camera relative pose estimation for visual servoing using quaternions
We present a novel approach to estimate the rotation and translation between two camera views from a minimum of five matched points in the images. Our approach simultaneously recovers the 3D structure of the points up to a common scale factor, and is immune to a variety of problems that plague existing methods that are based on the Euclidean homography or Essential matrix. Methods based on homography only function when feature points are coplanar in 3D space. Methods based on the Essential matrix often lose accuracy as the translation between two camera views goes to zero or when points are coplanar. By recovering the rotation and translation independently using quaternions, our algorithm eschews the shortcomings of these methods. Moreover, we do not impose any constraints on the 3D configuration of the points (such as coplanar or non-coplanar constraints). Our method is particularly well-suited for Position-Based Visual Servoing (PBVS) applications. Investigations using both simulations and experiments validate the new method. Comparisons between the proposed algorithm and the existing algorithms establish that our algorithm is robust to noise. A Matlab implementation of our algorithm is available online and free. © 20181
Health risk assessment of the European inhabitants exposed to contaminated ambient particulate matter by potentially toxic elements
PM10-associated potential toxic elements (PTEs) can enter the respiratory system and cause health problems. In the current study, the health risk indices caused by PM10 inhalation by adults, children, and infants in 158 European cities between 2013 and 2019 were studied to determine if Europeans were adversely affected by carcinogenic and non-carcinogenic factors or not. The Mann–Kendall trend test examined PM10's increasing or decreasing trend. Random Forest analysis was also used to analyse meteorological factors affecting PM10 in Europe. Hazard quotient and cancer risk were estimated using PM10-associated PTEs. Our results showed a decline in continental PM10 concentrations. The correlation between PM10 concentrations and temperature (−0.40), PBLH (−0.39), and precipitation were statistically strong (−0.21). The estimated Pearson correlation coefficients showed a statistically strong positive correlation between As & Pb, As & Cd, and Cd & Pb during 2013–2019, indicating a similar origin. PTEs with hazard quotients below one, regardless of subpopulation type, posed no noncancerous risk to Europeans. The hazard quotient values positively correlated with time, possibly due to elevated PTE levels. In our study on carcinogen pollution in Europe between 2013 and 2019, we found unacceptable levels of As, Cd, Ni, and Pb among adults, children, and infants. Carcinogenic risk rates were highest for children, followed by infants, adult women, and adult men. Therefore, besides monitoring and mitigating PM concentrations, effective control of PM sources is also needed.</p