A Computational Framework for Real-Time Unmanned Sea Surface Vehicle Motion Simulation

Unmanned Sea Surface Vehicle (USSV) motion simulation in time domain is an important component of USSV design and operation. This capability is needed for hull design, operator training, controller synthesis and testing. Many applications such as simulators for operator training require real-time performance. Traditional approaches based on strip theory, although fast, abstract hulls into slender bodies, making the simulation results insensitive to changes in geometry. Computational fluid dynamics (CFD) based approaches are accurate but very slow. Potential flow based approaches are sensitive to hull geometry and take lesser amount of time than CFD based approaches. The motion simulation using potential flow theory involves following four main operations: (1) computation of dynamic pressure head due to fluid flow around the hull under the ocean wave, (2) computation of wet surface, (3) computing surface integral of dynamic pressure head over wet surface, and (4) solving the rigid body dynamics equation. First three operations depend upon the boat geometry complexity and need to be performed at each time step, making the simulation run very slow. In this paper, we investigate the problem of model simplification for real-time simulation of USSV model in time domain using potential flow theory, with arbitrary geometry under ocean waves with inviscid and irrotational flow. Using clustering based simplification scheme and parallel computing we obtained real time simulation performance.