Browsing by Author "Viana, Nuno Manuel Couto"
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- Sistema de Posicionamento Acústico e Transmissão de Dados para Alvos SubaquáticosPublication . Viana, Nuno Manuel Couto; Martins, Alfredo Manuel OliveiraWith the increasing usage of unmanned underwater vehicles, the need to develop the different systems associated with them is also growing. One of the most essential systems for an unmanned vehicle is its positioning system. Due to the inherent characteristics of the medium, the most common positioning method in aquatic environments involves the use of acoustic signals that use time-of-flight measurements to locate a target, referencing it to a set of sensors. This dissertation presents an acoustic positioning system for underwater vehicles based on the measurement of arrival delays of three acoustic signals originating from emitters with known positions on the surface, providing data transmission by periodically sending a modulated signal with position information. This system includes several components. Firstly, there are three stationary emitters on the surface responsible for the periodic sending of modulated acoustic signals. Then, there is a receiver and an emitter on the target, the former being responsible for the acquisition of acoustic signals and the latter for sending an acoustic signal with the coded position. Finally, there’s a receiver on the surface responsible for capturing the signal with the coded position. The developed detection, coding and decoding algorithms are presented, as well as the hyperbolic positioning algorithm, the latter implemented with a Kalman filter for the position estimation. In addition, the development of hardware to enable the sending and reception of the acoustic signals is also analyzed. To validate the developed system, results obtained in field tests and in a simulation environment are presented.