LOTUSim: Open-source marine simulator for multi-drone fleet operations

LOTUSim is a new open-source, real-time maritime simulator developed by researchers from IMT Atlantique and CROSSING. It supports multi-user interaction across aerial, surface, and underwater robotic systems, enabling coordinated naval-style operations with large heterogeneous drone swarms. The simulator maintains strict real-time performance and high visual fidelity even with hundreds of simulated vehicles, making it suitable for operator training, mission rehearsal, and human-vehicle interaction research where real-world testing is costly or dangerous.

A key innovation is LOTUSim's computationally efficient, Ekman-inspired layered underwater current model. This model captures wind-driven, depth-dependent flow dynamics with significantly higher accuracy than the stochastic Gauss-Markov models commonly used in other simulators. Validation against ocean reanalysis data confirms the model's physical fidelity for large-scale simulations. The paper will be presented at IEEE IROS 2026.