{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,21]],"date-time":"2025-10-21T15:30:14Z","timestamp":1761060614419,"version":"3.41.2"},"reference-count":20,"publisher":"SAGE Publications","issue":"4","license":[{"start":{"date-parts":[[2018,7,1]],"date-time":"2018-07-01T00:00:00Z","timestamp":1530403200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"funder":[{"DOI":"10.13039\/501100011929","name":"POFC","doi-asserted-by":"crossref","award":["Grant agreement 2013\/034063 (SEAGULL, project numb"],"award-info":[{"award-number":["Grant agreement 2013\/034063 (SEAGULL, project numb"]}],"id":[{"id":"10.13039\/501100011929","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["International Journal of Advanced Robotic Systems"],"published-print":{"date-parts":[[2018,7,1]]},"abstract":"<jats:p> Unmanned air systems are becoming ever more important in modern societies but raise a number of unresolved problems. There are legal issues with the operation of these vehicles in nonsegregated airspace, and a pressing requirement to solve these issues is the development and testing of reliable and safe mechanisms to avoid collision in flight. In this article, we describe a sense and avoid subsystem developed for a maritime patrol unmanned air system. The article starts with a description of the unmanned air system, that was developed specifically for maritime patrol operations, and proceeds with a discussion of possible ways to guarantee that the unmanned air system does not collide with other flying objects. In the system developed, the position of the unmanned air system is obtained by the global positioning system and that of other flying objects is reported via a data link with a ground control station. This assumes that the detection of those flying objects is done by a radar in the ground or by self-reporting via a traffic monitoring system (such as automatic identification system). The algorithm developed is based on game theory. The approach is to handle both the procedures, threat detection phase and collision avoidance maneuver, in a unified fashion, where the optimal command for each possible relative attitude of the obstacle is computed off-line, therefore requiring low processing power for real-time operation. This work was done under the research project named SEAGULL that aims to improve maritime situational awareness using fleets of unmanned air system, where collision avoidance becomes a major concern. <\/jats:p>","DOI":"10.1177\/1729881418786338","type":"journal-article","created":{"date-parts":[[2018,7,12]],"date-time":"2018-07-12T02:43:44Z","timestamp":1531363424000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":5,"title":["An unmanned aircraft system for maritime operations"],"prefix":"10.1177","volume":"15","author":[{"given":"Mario Monteiro","family":"Marques","sequence":"first","affiliation":[{"name":"Escola Naval Centro de Investigacao Naval, Almada, Portugal"}]},{"given":"Victor","family":"Lobo","sequence":"additional","affiliation":[{"name":"Escola Naval Centro de Investigacao Naval, Almada, Portugal"}]},{"given":"R","family":"Batista","sequence":"additional","affiliation":[{"name":"Critical Software, R. Eng. Frederico Ulrich, Maia, Portugal"}]},{"given":"J","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Critical Software, R. Eng. Frederico Ulrich, Maia, Portugal"}]},{"given":"A Pedro","family":"Aguiar","sequence":"additional","affiliation":[{"name":"FEUP, Rua Dr. Roberto Frias, Porto, Portugal"}]},{"given":"J Estrela","family":"Silva","sequence":"additional","affiliation":[{"name":"FEUP, Rua Dr. Roberto Frias, Porto, Portugal"}]},{"given":"J Borges","family":"de Sousa","sequence":"additional","affiliation":[{"name":"FEUP, Rua Dr. Roberto Frias, Porto, Portugal"}]},{"given":"Maria de F\u00e1tima","family":"Nunes","sequence":"additional","affiliation":[{"name":"Portuguese Air Force Research Center, Granja do Marqu\u00eas, Sintra, Portugal"}]},{"given":"Ricardo Adriano","family":"Ribeiro","sequence":"additional","affiliation":[{"name":"University of Lisbon, Avenida Rovisco Pais 1, Lisbon, Portugal"}]},{"given":"Alexandre","family":"Bernardino","sequence":"additional","affiliation":[{"name":"University of Lisbon, Avenida Rovisco Pais 1, Lisbon, Portugal"}]},{"given":"Jorge Salvador","family":"Marques","sequence":"additional","affiliation":[{"name":"University of Lisbon, Avenida Rovisco Pais 1, Lisbon, Portugal"}]}],"member":"179","published-online":{"date-parts":[[2018,7,11]]},"reference":[{"volume-title":"Maritime domain awareness: the key to maritime security. Leg challenges","year":"2008","author":"Nimmich J","key":"bibr1-1729881418786338"},{"volume-title":"Avoiding collisions between aircraft: state of the art and requirements for UAVs operating in civilian airspace","year":"2008","author":"Geyer CM","key":"bibr2-1729881418786338"},{"key":"bibr3-1729881418786338","doi-asserted-by":"publisher","DOI":"10.1007\/s10846-015-0291-2"},{"first-page":"591","volume-title":"IEEE conference on decision and control and European control conference","author":"Bencatel R","key":"bibr4-1729881418786338"},{"volume-title":"AIAA 3rd unmanned unlimited technical conference","author":"Schaeffer RA","key":"bibr5-1729881418786338"},{"first-page":"4357","volume-title":"47th IEEE conference on decision and control","author":"Hoffmann MG","key":"bibr6-1729881418786338"},{"key":"bibr7-1729881418786338","doi-asserted-by":"crossref","unstructured":"Yu X, Zhang Y. Sense and avoid technologies with applications to unmanned aircraft systems: review and prospects. 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