5 research outputs found
Singularity-free Guiding Vector Field for Robot Navigation
Most of the existing path-following navigation algorithms cannot guarantee
global convergence to desired paths or enable following self-intersected
desired paths due to the existence of singular points where navigation
algorithms return unreliable or even no solutions. One typical example arises
in vector-field guided path-following (VF-PF) navigation algorithms. These
algorithms are based on a vector field, and the singular points are exactly
where the vector field diminishes. In this paper, we show that it is
mathematically impossible for conventional VF-PF algorithms to achieve global
convergence to desired paths that are self-intersected or even just simple
closed (precisely, homeomorphic to the unit circle). Motivated by this new
impossibility result, we propose a novel method to transform self-intersected
or simple closed desired paths to non-self-intersected and unbounded
(precisely, homeomorphic to the real line) counterparts in a higher-dimensional
space. Corresponding to this new desired path, we construct a singularity-free
guiding vector field on a higher-dimensional space. The integral curves of this
new guiding vector field is thus exploited to enable global convergence to the
higher-dimensional desired path, and therefore the projection of the integral
curves on a lower-dimensional subspace converge to the physical
(lower-dimensional) desired path. Rigorous theoretical analysis is carried out
for the theoretical results using dynamical systems theory. In addition, we
show both by theoretical analysis and numerical simulations that our proposed
method is an extension combining conventional VF-PF algorithms and trajectory
tracking algorithms. Finally, to show the practical value of our proposed
approach for complex engineering systems, we conduct outdoor experiments with a
fixed-wing airplane in windy environment to follow both 2D and 3D desired
paths.Comment: Accepted for publication in IEEE Trransactions on Robotics (T-RO
Proceedings of the International Micro Air Vehicles Conference and Flight Competition 2017 (IMAV 2017)
The IMAV 2017 conference has been held at ISAE-SUPAERO, Toulouse, France from Sept. 18 to Sept. 21, 2017. More than 250 participants coming from 30 different countries worldwide have presented their latest research activities in the field of drones. 38 papers have been presented during the conference including various topics such as Aerodynamics, Aeroacoustics, Propulsion, Autopilots, Sensors, Communication systems, Mission planning techniques, Artificial Intelligence, Human-machine cooperation as applied to drones
Abstracts on Radio Direction Finding (1899 - 1995)
The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography).
Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM.
The contents of these files are:
1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format];
2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format];
3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion