Open-source Simulation of Underwater Gliders

Abstract

Autonomous underwater gliders (AUGs) are currently deployed in oceans throughout the globe and are recording real-time, in-situ data. Simulating AUGs is rendered particularly difficult by the identification of the underlying dynamic model, as these vehicles embed several internal movable components. Acausal simulators can significantly improve the possibility to study and understand the dynamics of this class of vehicles and can in turn support the design of more robust control systems. In this paper, an open-source simulator architecture designed in OpenModelica is proposed to simulate underwater gliders. The validation is carried out using two different AUGs models, a ROGUE and a Seawing. The vehicle dynamics is firstly compared with analytical results and, following, with values obtained by means of another simulator. Further steps will entail comparing the dynamics of a simulated Seaglider with real deployment data publicly available. In this work, some of the main hydrodynamic and geometrical properties of a Seaglider are identified, computed through Computational Fluid Dynamics (CFD) analyses and retrieved from the mission ballast sheet. Overall, the developed model is expected to enhance gliders’ control strategies, thus improving their performance and mitigating incidents such as being carried away by undesired ocean currents.