Manoeuvrability is one of the essential keys in the development of improved autonomous underwater vehicles for challenging missions. In the last years, more researches were dedicated to the development of new hulls shapes and thrusters to assure more manoeuvrability. The present review explores various enabling technologies used to implement the vectorial thrusters (VT), based on water-jet or propellers. The proposals are analysed in terms of added degrees of freedom, mechanisms, number of necessary actuators, water-tightness, electromagnetomechanical complexity, feasibility, etc. The usage of magnetic coupling thrusters (conventional or reconfigurable) is analysed in details since they can assure the development of competitive full waterproof reconfigurable thrusters, which is a frictionless, flexible, safe, and low-maintenance solution. The current limitations (as for instance the use of non conductive hull) are discussed and ideas are proposed for the improvement of this new generation of underwater thrusters, as extending the magnetic coupling usage to obtain a fully contactless vector thrust transmission.

This paper presents an evaluation method for assessing different Autonomous Underwater Vehicle (AUV) propulsion systems (or topologies). This evaluation is based on solid/fluid dynamics simulation and uses a model-based control (feedback linearisation) to achieve the robotic mission assigned to the AUV. The objective of this work is to provide an evaluation relevant enough to be used for optimisation purposes. A model of an existing AUV (RSM) is proposed and detailed as well as two studied propulsion systems in competition: Fixed and vectorial thrusters. The main contribution of this work is to bring a consistent evaluation including models, tasks and a generic high-level control adapted to each system. Simulations of our AUV achieving a diving task are carried out for both propulsion systems. The simulated task analysis allows to evaluate the influence of the propulsive strategy over AUVs operability. Subsequently, numerical results are discussed in terms of energy efficiency and control.

The concept of reconfigurable magnetic coupling thrusters (RMCT) applied to the vectorial thrust of autonomous underwater vehicles (AUV) has been recently developed and presented. This technology ensures greater robot watertightness with enhanced maneuvering capabilities, which are desired features in agile AUVs for marine renewable energy (MRE) system maintenance. It is possible since in RMCTs the driving torque is magnetically transmitted to the propeller, which has its orientation changed. This work is focused on the coupling and control torque calculation and further analysis of the latest prototype version (Flat-RMCT), in the static condition for the full thrust vector range. For this purpose, a numerical model is implemented and validated with experimental results. The numerical model is based on the finite volume integral method. The results indicate that the minimum magnetic reluctance propensity creates not only the expected magnetic spring effect but also an auto-driving torque due to the non-axial symmetry of coupling rotors, which exists only for reconfigurable couplings. Mathematical functions are proposed to model these effects and they are used to extend the understanding of the coupling. These models can be used to compose a full and accurate dynamic model for a better RMCT simulation, identification, and control.

This article proposes a methodology for monitoring the structural stability of each tower of an electric power transmission line through sensor measurements which estimates the different situations that may indicate the need for intervention to prevent the structure collapsing. The extended Kalman filter was adopted to predict the failures, considering sensor fusion techniques such as the displacements of the upper central position of the tower above certain limits. The load of the stay cables is calculated from the natural frequencies, which are determined by the accelerometers connected to the cables. The average value of these forces, which must be higher than a normal limit, were calculated to predict a failure. All guyed towers of a power transmission line thousands of kilometers long will be individually monitored considering the methodology described in this study, which makes this article one of the first relevant research studies in this area. Typically, guyed towers must often be manually inspected to ensure that the stay cables have acceptable pretension to prevent a lack of stability in the transmission line towers.

Em meio à crescente preocupação com emissões de gases poluentes em grandes centros urbanos e à busca por melhoria da eficiência energética no setor de tr...