Navegação Acústica Passiva

Abstract

This thesis, done in order of master degree in Electrical Engineering and Computers, inserted in the activities of the Robotics Unity and Intelligent Systems of INESC TEC, aims the development of a system capable of tracking and estimate the position, in real time, of an autonomous underwater vehicle. To locate the AUV, its used points of reference installed in buoys, with known positions for the vehicle. This buoys are responsible to send acoustic signals that are detected by the AUV registering the time of arrival. This data is used to estimate the distance between the vehicle and the buoys, which is later to triangulate an estimated position of the vehicle. The importance of this project is related is how this system communicates, that is passively, the vehicle only listen to the emitter, which are the buoys. This property reduces, by half, the exchange of signals between the emitter and the receptor, and consequently, a better energy efficiency, which is related to the fact that the AUV only listen to the buoys. The greater difficulty of this systems, is associated to the fact of the inexistency of clock synchronism between the buoys and the AUV. This characteristic brings many benefices, which as lesser complexity of the hardware and there is no need to sync all the clocks in the system every time a cycle begins, in the other hand, the complexity of the mathematical algorithm increases, and therefore, the computation complexity as well. In this document, will be related the process of the development of various algorithms crucial to the functioning of the system. The trajectory and the progress of the vehicle will be presented in real time.